MATERIALS AND SOCIETY*
MATERIALS AND SOCIETY
The field of materials is immense and diverse. Historically, it began with the emergence of man himself, and materials gave name to the ages of civilization. Today, the field logically encompasses the lonely prospector and the advanced instrumented search for oil; it spreads from the furious flame of the oxygen steelmaking furnace to the quiet cold electrodeposition of copper; from the massive rolling mill producing steel rails to the craftsman hammering out a chalice or a piece of jewelry; from the smallest chip of an electronic device to the largest building made by man; from the common paper-bag to the titanium shell of a space ship; from the clearest glass to carbon black; from liquid mercury to the hardest diamond; from superconductors to insulators; from the room-temperature casting plastics to infusible refractories (except they can be melted today); from milady’s stocking to the militant’s bomb; from the sweating blacksmith to the cloistered contemplating scholar who once worried about the nature of matter and now tries to calculate the difference between materials.
Materials by themselves do nothing; yet without materials man can do nothing. Nature itself is a self-ordered structure which developed through time by the utilization of the same properties of atomic hierarchy that man presides over in his simple constructions.
One of the hallmarks of modern industrialized society is our increasing extravagance in the use of materials. We use more materials than ever before, and we use them up faster. Indeed, it has been postulated that, assuming current trends in world production and population growth, the materials requirements for the next decade and a half could equal all the materials used throughout history up to date.1 This expanding use of materials is itself revolutionary, and hence forms an integral part of the “materials revolution” of our times.
Not only are we consuming materials more rapidly, but we are using an increasing diversity of materials. A great new range of materials has opened up for the use of 20th-century man: refractory metals, light alloys, plastics, and synthetic fibers, for example. Some of these do better, or cheaper, what the older ones did; others have combinations of properties that enable entirely new devices to be made or quite new effects to be achieved. We now employ in industrial processes a majority of the ninety-two elements in the periodic table which are found in nature, whereas until a century ago, all but 20, if known at all, were curiosities of the chemistry laboratory.2 Not only are more of nature’s elements being put into service, but completely new materials are being synthesized in the laboratory. Our claim to a high level of materials civilization rests on this expanded, almost extravagant utilization of a rich diversity of materials.
This extravagance is both a product of advances in materials and a challenge in its future growth. The enlarged consumption of materials means that we will have to cope increasingly with natural-resource and supply problems. Mankind is being forced, therefore, to enlarge its resource base—by finding ways to employ existing raw materials more efficiently, to convert previously unusable substances to useful materials, to recycle waste materials and make them reusable, and to produce wholly new materials out of substances which are available in abundance.
The expanded demand for materials is not confined to sophisticated space ships or electronic and nuclear devices. In most American kitchens are new heat-shock-proof glasses and ceramics—and long-life electric elements to heat them; the motors in electric appliances have so-called oilless bearings which actually hold a lifetime supply of oil, made possible by powder metallurgy; the pocket camera uses new compositions of coated optical glass; office copy-machines depend on photoconductors; toy soldiers are formed out of plastics, not lead; boats are molded out of fiberglass; the humble garbage can sounds off with a plastic thud rather than a metallic clank; we sleep on synthetic foam mattresses and polyfiber pillows, instead of cotton and wool stuffing and feathers; we are scarcely aware of how many objects of everyday life have been transformed—and in most cases, improved—by the application of materials science and engineering (MSE). Moreover, as with a rich vocabulary in literature, the flexibility that is engendered by MSE greatly increases the options in substitutions of one material for another.
Quite often the development of a new materials or process will have effects far beyond what the originators expected. Materials have somewhat the quality of letters in the alphabet in that they can be used to compose many things larger than themselves; amber, gold jewelry, and iron ore inspired commerce and the discovery of many parts of the world; improvements in optical glass lies behind all the knowledge revealed by the microscope; conductors, insulators, and semiconductors were needed to construct new communication systems which today affect the thought, work, and play of everyone. Alloy steel permitted the development of the automobile; titanium the space program. The finding of a new material was essential for the growth of the
laser, the social uses of which cannot yet be fully imagined. In these, as in hundreds of other cases, the materials themselves are soon taken for granted, just as are the letters of a word. To be sure, the ultimate value of a material lies in what society chooses to do with whatever is made of it, but changes in the “smaller parts” reacting responsibly to larger movements and structures make: it possible to evolve new patterns of social organization.
The transitions from, say, stone to bronze and from bronze to iron were revolutionary in impact, but they were relatively slow in terms of the time scale. The changes in materials innovation and application within the last half century occur in a time span which is revolutionary rather than evolutionary.
The materials revolution of our times is qualitative as well as quantitative. It breeds the attitude of purposeful creativity rather than modification of natural materials, and also a new approach—an innovative organization of science and technology. The combination of these elements which constitutes materials science and engineering (MSE) is characterized by a new language of science and engineering, by new tools for research, by a new approach to the structure and properties of materials of all kinds, by a new interdependence of scientific research and technical development, and by a new coupling of scientific endeavor with societal needs.
As a field, MSE is young. There is still no professional organization embodying all of its aspects, and there is even some disagreement as to what constitutes the field. One of the elements which is newest about it is the notion of purposive creation. However, MSE is responsive as well as creative. Not only does it create new materials, sometimes before their possible uses are recognized, but it responds to new and different needs of our sophisticated and complex industrial society. In a sense, MSE is today’s alchemy. Almost magically, it transmutes base materials, not into gold—although it can produce gold-looking substances—but into substances which are of greater use and benefit to mankind than this precious metal. MSE is directed toward the solution of problems of a scientific and technological nature bearing on the creation and development of materials for specific uses; this means that it couples scientific research with engineering applications of the end-product: one must speak of materials science and engineering as an “it” rather than “them.”
Not only is MSE postulated on the linkage of science and technology, it draws together different fields within science and engineering. From technology, MSE brings metallurgists, ceramists, electrical engineers, chemical engineers; from science it embraces physicists, inorganic chemists, organic chemists, crystallographers, and various specialists within those major fields.
In its development, MSE not only involved cooperation among different branches of science and engineering, but also collaboration among different kinds of organizations. Industrial corporations, governmental agencies, and universities have worked together to shape the outlines and operations of this new “field.”
In recent years there has been a marked increase in the liaison between industrial production and industrial research, and between research in industry and that in the universities. The researcher cannot ignore problems of production, and the producer knows that he can get from the scientist
suggestions for new products and sometimes help for difficulties. It should be noticed that MSE has come about by the aggregation of several different specialties that were earlier separate, not, as so often happens, by growth of increased diversity within a field which keeps some cohesion. This change is just as much on the industrial side as it is on the academic. Industry continually uses its old production capabilities on new materials, and the scientist finds himself forced to look at a different scale of aggregation of matter.
Most of the work on materials until the 20th century was aimed at making the old materials available in greater quantity, of better quality, or at less cost. The new world in which materials are developed for specific purposes (usually by persons who are concerned with end-use rather than with the production of the materials themselves) introduces a fundamental change, indeed. Heretofore, engineers were limited in their designs to the use of materials already “on the shelf.” This limitation no longer applies, and the design of new materials is becoming a very intimate part of almost every engineering plan. MSE interacts particularly well with engineers who have some application in mind. It often reaches the general public through secondary effects, such as negatively via the pollution which results from mining, smelting, or processing operations, and positively via the taken-for-granted materials that underly every product and service in today’s complicated world. The provision of materials for school children and mature artists is one of the more positive contacts with the public, Of course, most materials existed long before MSE aided in their development, but now it does provide the guidelines for future change.
The rising tide of “materials expectations” is not for the materials themselves, but for things which of necessity incorporate materials. That materials are secondary in most end-applications is obvious from the name applied to the materials that remain when a machine or structure no longer serves its purpose— “junk.” There is, however, at least one positive direct contact, that of waste-material processing; for city waste disposal is a very challenging materials-processing problem, especially if the entire cycle from production, use, and reuse of materials can be brought into proper balance.
As one cynical observer put it, “For the first two decades of its existence, materials science and engineering was engaged in producing new and better products for mankind; the major task of materials science and engineering for the next two decades is to help us get rid of the rubbish accumulated because of the successes of the past twenty years.”
IMPORTANCE OF MATERIALS TO MAN
Materials are so ubiquitous and so important to man’s life and welfare that we must obviously delimit the term in this survey, lest we find ourselves investigating nearly every aspect of science and technology and describing virtually every facet of human existence and social life. Unless we limit our scope, all matter in the universe will inadvertently be encompassed within the scope of our survey.
But matter is not the same as material. Mainly we are concerned with materials that are to become part of a device or structure or product made by
man. The science part of MSE seeks to discover, analyze and understand the nature of materials, to provide coherent explanations of the origin of the properties that are used, while the engineering aspect takes this basic knowledge and whatever else is necessary (not the least of which is experience) to develop, prepare, and apply materials for specified needs, often the most advanced objectives of the times. It is the necessarily intimate relationship between these disparate activities that to some extent distinguishes MSE from other fields and which makes it so fascinating for its practitioners. The benefits come not only from the production of age-old materials in greater quantities and with less cost—an aspect which has perhaps the most visible influence on the modern world, but it also involves the production of materials with totally new properties. Both of these contributions have changed the economy and social structure, and both have come about in large measure through the application of a mixture of theoretical and empirical science with entrepreneurship. And just as the development of mathematical principles of design enabled the 19th-century engineer to test available materials and select the best suited for his constructions, so the deeper understanding of the structural basis of materials has given the scientist a viewpoint applicable to all materials, and at every stage from their manufacture to their societal use and ultimate return to earth.
The production of materials has always been accompanied by some form of pollution, but this only became a problem when industrialization and population enormously increased the scale of operation. Longfellow’s poem contains no complaint about the smoke arising from the village smithy’s forge; if one of today’s poets would attempt to glorify the blacksmith’s modern counterpart, he would undoubtedly describe the smoke belching forth from the foundry, but there would be no mention of spreading chestnut trees because all those within a half-mile’s radius would long ago have withered from the pollution of the surrounding neighborhood. The simple fact is that an industrial civilization represents more activity, more production, and usually more pollution, even though the pollution attributable to each unit produced may be sharply decreased.
The utilization of materials, as well as their manufacture, also generates pollution. Those of us living in affluent, highly industrialized countries enjoy the benefits of a “throw-away” society. The problem arises from the fact that many of the products we use are made from materials which are not strictly “throw-awayable.” Natural processes do not readily return all materials to the overall cycle, and in the case of certain mineral products, we can sometimes find no better way of disposing of scrap than to bury it back in the earth from which we had originally extracted it at great trouble and expense. Proposals for reuse or recycling often founder upon public apathy—but this is changing, and MSE has an important role to play.
The moral and spiritual impact of materials on both consumer and producer is both less visible and more debatable. To those reared in a Puritanical ethic of self-denial, the outpouring of materials goods would seem almost sinful, as would the waste products of a throw-away society. Such conspicuous consumption would seem almost immoral in a world where so many people are still lacking basic material essentials. A more sophisticated objection might be that the very profusion of materials presents modern man with psychological dilemmas. We are presented with so many options that we
find it difficult to choose among them.3
It might be surprising to some that the question of the debasement of the materials producer should even be raised. Scientists have long claimed that their pursuit of an understanding of nature is innocent, and technologists have always assumed that their gifts of materials plenty to mankind would be welcomed. Hence, it has come as a shock to them during the past few years that the benefits of science and technology have been questioned. Both science and technology have been subjected to criticism from highly articulate members of the literature subculture, as well as from within their own ranks, regarding their contributions to mankind’s destructive activities and to the deterioration of the environment.4
To those engaged in materials production and fabrication, it may be disconcerting to realize that for a fair fraction of human history their activities have been viewed with suspicion and downright distaste by social thinkers and by the general public. The ancient Greek philosophers, who set the tone for many of the attitudes still prevalent throughout Western Civilization, regarded those involved in the production of material goods as being less worthy than agriculturists and others who did not perform such mundane tasks. Greek mythology provided a basis for this disdain: the Greek Gods were viewed as idealistic models of physical perfection; the only flawed immortal was the patron god of the metalworker, Hephaestus, whose lameness made him the butt of jokes among his Olympian colleagues, (But he got along well with Aphrodite, another producer!)
Throughout ancient society the most menial tasks, especially those of mining and metallurgy, were left to slaves. Hence, the common social attitude of antiquity, persisting to this day in some intellectual circles, was to look down upon those who worked with their hands. Xenophon5 stated the case in this fashion: “What are called the mechanical arts carry a social stigma and are rightly dishonored in our cities. For these arts damage the bodies of those who work at them or who act as overseers, by compelling them to a sedentary life and to an indoor life, and, in some cases, to spend the whole day by the fire. This physical degeneration results also in deterioration of the soul. Furthermore, the workers at these trades simply have not got the time to perform the offices of friendship or citizenship. Consequently they are looked upon as bad friends and bad patriots, and in some cities, especially the warlike ones, it is not legal for a citizen to ply a mechanical trade.”
The ancients appreciated material goods but they did not think highly of those who actually produced them. In his life of Marcellus, Plutarch delivered this critical judgment, “For it does not of necessity follow that, if the work delights you with its grace, the one who wrought it is worthy of esteem.” The current apprehension concerning dangers to the environment from materials production might result in materials scientists and engineers being regarded with similar suspicion today.
But there is yet a subtler way in which the triumphs of MSE might threaten the spirit of Western man. Advances in materials have gone beyond the simple task of conquering nature and mastering the environment. MSE attempts to improve upon nature. In a sense, this represents the ancient Greek sin of hubris, inordinate pride, where men thought they could rival or even excel the gods—and retribution from the gods followed inevitably. This may also be “original sin,” the Christian sin of pride, which caused Adam’s fall. By eating the fruit of the tree of knowledge, Adam thought that he would know as much as God. Conceivably, by endeavoring to outdo nature modern man is preparing his own fall. Or perhaps his new knowledge will lead to control as well as power, and a richer life for mankind.
MATERIALS IN THE EVOLUTION OF MAN AND IN PREHISTORY
The very essence of a cultural development is its interrelatedness. This survey places emphasis on materials, but it should be obvious that materials per se are of little value unless they are shaped into a form that permits man to make or do something useful, or one that he finds delightful to touch or to contemplate. The material simply permits things to be done because of its bulk, its strength or, in more recent times, its varied combinations of physical, chemical, and mechanical properties. The internal structure of the material that gives these properties is simply one stage in the complex hierarchy of physical and conceptual structures that make up the totality of man’s works and aspirations.
We do not know exactly when our present human species, homo sapiens, came into being, but we do know that materials must have played a part in the evolution of man from more primitive forms of animal primates. It was the interaction of biological material and cultural processes that differentiated man from the rest of the animal world.6 Other animals possess great physical advantages over man: the lion is stronger, the horse is faster, the giraffe has a greater reach for food. Nevertheless, man possesses certain anatomical features which prove particularly useful in enabling him to deal with his environment.7
Modern physical anthropologists believe that there is a direct connection between such cultural traits as toolmaking and tool-using, and the development of man’s physical characteristics, including his brain and his hand.8 Man would not have become Man the Thinker (homo sapiens) had he not at the same time been Man the Maker (homo faber). Man made tools, but tools also made man. Perhaps man did not throw stones because he was standing up; he could have learned to stand erect the better to throw stones.
It is probable that the earliest humans used tools rather than made them, that is, they selected whatever natural objects were at hand for immediate use before they anticipated a possible future task and prepared the tools for it. Once this idea was formulated and man began to discover and test out things for what they could do, he found natural objects—sticks, fibers, hides—and combined materials and shapes to serve his purposes. He tried bones and horn, but the hardest and densest material at hand was stone. When he further learned how to form materials as well as select them, and to communicate his knowledge, civilization could begin; it appears there was a strong evolutionary bias towards anatomical and mental types that could do this. While the early stages still remain the realm of hypothesis, there is general agreement that it was over two million years ago when a pre-human hominid began to use pebbles or stones as tools, though the shaping of specialized tools came slowly.
The recognition that there had been a cultural level to which we now give the name of Stone Age—itself a tribute to the importance of materials in man’s development—did not occur until well into the 19th century. When, about 1837, the Frenchman Boucher de Perthes propounded the view that some oddly-shaped stones were not “freaks of nature” but were the result of directed purposeful work by human hands, he was ridiculed. Only when the vastness of geological time scales was established and it became possible to depart from a literal interpretation of biblical genesis could credence be given to the notion that these stones were actually tools.9
Some of the features of today’s materials engineering can already be seen in the selection of flint by our prehistoric forebears as the best material for making tools and weapons. Availability, shapability, and serviceability are balanced. The brittleness of flint enabled it to be chipped and flaked into specialized tools, but it was not too fragile for service in the form of scrapers, knives, awls, hand axes, and the like. The geopolitical importance of material sources also appears early. It is perhaps not surprising that we find the most advanced early technologies and societies developing where
good-quality flint was available. It may even be, as Jacobs has surmised10, that cities arose from flint-trading centers and that the intellectual liveliness accompanying the cultural interchange of travellers then created the environment in which agriculture originated.
The pattern of human settlement from prehistoric times to our contemporary world has been determined in large measure by the availability of materials and the technological ability to work them.
Man could survive successive ice ages in the Northern Hemisphere without migrating or developing a shaggy coat like the mammoth because he had found some means of keeping himself warm—with protective covering from the skins of animals which, with his wooden and stone weapons, he could now hunt with some degree of success, but also, perhaps principally, by the control of fire, which became one of his greatest steps in controlling his environment. By the beginning of Palaeolithic (early Stone Age) times—between 800,000 and 100,000 years ago—man could produce fire at will by striking lumps of flint and iron pyrites against each other to produce sparks with which tinder, straw, or other flammable materials could be ignited.
Man’s control and use of fire had immense social and cultural consequences. With fire he could not only warm his body but could also cook his food, greatly increasing the range of food resources and the ease of its preservation. Claude Levi-Strauss, the French anthropologist famous for his “structuralist” approach to culture, claims that the borderline between “nature” and “culture” lies in eating one’s meat raw or eating it cooked.11 By their role in producing and fueling fires, materials thus played a significant part in the transition from “animal-ness” to “human-ness,” but more than that, fire provided a means of modifying and greatly extending the range of properties available in materials themselves.
Every cultural conquest, such as the use of fire, requires other cultural developments to make its use effective, and it also has unanticipated consequences in totally unforeseen areas. Containers were needed for better fire and food. The invention of pots, pans, and other kitchen utensils made it possible to boil, stew, bake, and fry foods as well as to broil them by direct contact with the fire. The cooking itself, and the search for materials to do it in, was perhaps the beginning of materials engineering! Furthermore, though the molding and fire hardening of clay figurines and fetishes had preceded the useful pot, it was the latter that, in the 8th millenium B.C., gave rise to the development of industry. Clay was the first inorganic material to be given completely new properties as a result of an intentional operation upon it by human beings. Though stone, wood, hides, and bone had earlier been beautifully formed into tools and utensils, their substance had remained essentially unchanged. The ability to make a hard stone from soft and moldable clay not only unfolded into useful objects, but the realization that man could change the innermost nature of natural materials must have had a profound impact upon his view of his powers; it gave him confidence to search for new materials at an ever increasing rate.
It was in the decoration of pottery that man first experimented with the effects of fire upon a wide range of mineral substances. Glazing, the forerunner of glass, certainly came therefrom, and it is probable that experiments with mineral colors on pottery led to the discovery of the reduction of metals from their ores toward the end of the 5th millennium B.C. Even earlier, man’s urge to art had inspired the discovery and application of many metallic minerals as pigments.12
From late Paleolithic times come the great cave paintings representing hunting scenes in realistic detail, executed with such mastery that, when they were discovered by chance in the caves at Altamira, Spain in 1879 and later in Lascaux, France, many found it difficult to believe that they had been done by primitive man. These paintings provide the earliest evidence of man’s awareness of the special properties of iron ore, manganese ore, and other minerals. He sensed qualitative differences that depended on chemical and physical properties quite invisible to him, on which eventually could be based a metallurgical industry.
Even before he learned to paint, early man had sensitively used the properties of other materials in art. He had made sculpture in ivory, stone, rock, clay, and countless more-perishable materials. Though it is often said that his ability to do this came from the increased leisure time released by the efficiency of his hunting following the development of tools and weapons, it is more likely that the exercise of his explorative tendencies, his aesthetic curiosity, was one of the factors from the very first that gave him a unique evolutionary advantage among other animals. Interaction with materials at this level was both easy and rewarding, and it was probably a necessary preliminary to the selection of the more imaginative and adaptable biological mutants that were to follow. In culture as in biology, man possessed more than the rudiments of technology when he had discovered and prepared his materials for painting and had developed methods of working them with fingertip and brush, crayons, and spray. He also had used specialized tools to sculpt stone and to mold clay at about the same time he learned to finish stone abrasively, and so was freed from dependence on flakeable flint since he could then adapt commoner, harder, polycrystalline rocks such as basalt and granite for his tools.
As in the case of the use of fire by man, the next great innovation in another field of technology, agriculture, was accompanied by a diverse series of auxiliary changes. Man had to develop a whole new set of tools: the hoe to till the ground, the sickle to reap the grain, some kind of flail to thresh the grain, and the quern (mill) to grind it. These tools were made of stone and wood; they were not very efficient. Nevertheless, agriculture was able to provide man with a surer source of food than could be obtained through the older technology of hunting, and it required concomitant advances in materials. Not the least important were fired ceramics which provided the pots needed for cooking, as well as larger containers for rodent-proof storage of crops.
The introduction of agriculture meant that the supply of animal skins from hunting was diminished, Man had to find substitutes among vegetable fibers, things such as reeds, flax, or cotton, and to utilize the hair of the animals which he had learned to domesticate. Some of these fibers had been used before, especially in woven mats, fences, building components, and basketry, but mainly for clothing. So textiles developed, and textiles inspired new machines: a spinning device (the spindle with its inertia-driven whorl) and a loom for weaving the threads into cloth. The patterns he worked into textiles and painted on his pots gave him practical contact with elements of geometry and with the relationships between short-range symmetry and long-range pattern which reappear in today’s structure-based science.
Because the implements and weapons of our prehistoric forebears are crude and primitive in comparison with today’s materials and machines, we should not be misled into downgrading the degree of skill which Stone Age man possessed. When, a few years ago, a class at the University of California was provided with a pile of flintstones and given the task of shaping simple stone implements from them, they found that even after many hours of repeated trials, they could not produce a tool that would have sufficed even for a run-of-the-mill Stone Age man.13 But experience breeds skill, and it is discovery of the possibilities and their interaction with other aspects of culture, not mere duplication, that paces “progress.”
The great Neolithic technological revolution—with its development of agriculture and fairly large-scale settled communities—occurred some tens upon tens of thousands of years after man had already mastered his implements of stone and had achieved his intellectual and physical evolution. It set into movement a whole series of technological and cultural changes within the next two millenia which thoroughly transformed man’s relations with nature and with his fellow man, and, most important, his thoughts about change and his prospects of the future. While the process might seem slow to us today, it was dynamic by the standards of the preceding ages.
Whether or not the urban society preceded or followed the agricultural revolution, it seems almost certain that the city provided conditions that accelerated man’s journey along the path towards civilization; indeed, the two are almost synonymous. During the period from about 5000 to 3000 B.C., two millenia after the introduction of agriculture, a series of basic inventions appeared,14 Man developed a high-temperature kiln, he learned to smelt and employ metals, and to harness animals. He invented the plow, the wheeled cart, the sailing ship, and writing. Communication and commerce based on specialized skills and localized raw materials both enabled and depended upon central government together with reinforcing religious, social, and scientific concepts. The great empires in Mesopotamia and Egypt, the
forerunners of our Western civilization, were based on the interaction of many institutions and ideas, but materials were necessary for them to become effective. Indeed, the characteristics of this early period are mainly an interplay between principles of human organization and the discovery of the properties of matter as they resided in a wide diversity of materials. Both tools and buildings were simple; mechanisms comparable in ingenuity to the materials used in the decorative arts of Sumer, Egypt, and Greece do not appear until much latter. All, as far as we can tell, were based on experience and empiricism with little help from theory.
BRONZE AND IRON AGES
Stone was eventually supplemented by copper, and copper led to bronze. Near the end of the period under discussion, bronze in turn was partially displaced by iron. So important is the change in materials base of a civilization that the materials themselves have given rise to the names of the ages—the Stone Age, the Bronze Age, and the Iron Age. In the 19th century after much groundwork both literally and figuratively by geologists, paleontologists, and archeolegists, these terms came to supersede both the poets gold and silver ages and the philosopher’s division of the past into periods based on religious, political, or cultural characteristics.15
There were no sharp chronological breaking points between the three ages, nor did the switch from one material to another take place everywhere at the same time. Even, for example, in those areas where bronze tools and weapons came into use, stone tools and weapons remained on the scene for a long time. Similarly, iron did not Immediately replace bronze, and indeed, there were still some civilizations which passed directly from stone to iron and some which, from indifference or from lack of knowledge, never adopted either metal. As a matter of fact, the first tools and weapons of iron were probably inferior to the contemporary bronze tools whose technology had been known for over two millennia. At first, the advantage of iron over bronze was based on economics, not superior quality. Iron was laborious to melt, but it could be made from widespread common minerals. A monarch could arm his entire army with iron swords, instead of just a few soldiers with bronze swords when the rest would have to fight with sticks and bows and arrows. With iron came a quantitative factor that had profound social, economic, and political consequences for all aspects of culture.16
Native metals, like gold, silver, and copper, were hammered into decorative objects during the 8th millennium B.C. in an area stretching from Anatolia to the edge of Iran’s central desert, during the 5th millennium B.C. in the Lake Superior region of North America, and during the mid-2nd millennium B.C. in South America. However, it was not until man learned to smelt
metals and reduce them from their ores, to melt and cast them, that metallurgy proper can be said to have begun. Again, the early advantage was only an economic one, the mineral ores of copper being vastly more abundant than is the native metal, but the way was opened for alloying and the discovery of entirely unsuspected properties. Moreover, with molten metal, casting into complicated shapes became possible,
The discovery of smelting has left no records, Given the availability of adequately high-temperatures in pottery kilns and the use of metal oxides for decoration, drops of reduced metal could well have been produced repeatedly before the significance was grasped. But once it was, empirical experiments with manipulation of the fire and the selection of the appropriate heavy, colored minerals would have given the desired materials with reasonable efficiency. A kiln works best with a long-flame fuel such as wood; smelting is best done with charcoal and with a blast from a plowpipe or bellows, but the time when these were first used has yet to be established. The first alloys were probably made accidentally in the smelting of a copper ore containing arsenic and/or antimony, which improve both the castability and the hardness without undue loss of the essential metallic property of malleability. For a thousand years, these alloys were exploited, until finally they were largely replaced by bronze, an alloy made from a heavy readily identifiable, though scarce, mineral, and having somewhat superior properties to those of the copper-arsenic alloys; there was also the added advantage that those who knew how to use it lived longer!
A lively argument is currently going on among archeologists as to whether the original discovery of bronze took place in the region of Anatolia and the adjacent countries to the South and East or in Eastern Europe—or independently in both.17 Whatever the evolutionary process of the development of metallurgy, there is no doubt that it had profound social, economic, and political consequences.
Though the earliest stone industry and commerce had required some organized system of production, and division of labor was well advanced in connection with large irrigation and building projects,18 the use of metals fostered a higher degree of specialization and diversity of skills; it also required communication and coordination to a degree previously unknown. Both trade and transportation owe much of their development to the requirements of materials technology: not only ores, requiring bulk transportation over great distances from foreign lands, but also precious objects for the luxury trade, such as amber, gem stones, gold and silver jewelry, fine decorated ceramics, and eventually glass.
The search for ways of working materials prompted man’s first use of machines to guide the power of his muscles. Rotary motion had many applications that were more influential than the well-known cartwheel. Perhaps
beginning with the child’s spinning top, it was the basis of many devices, the most important of which were the drill for bead-making, stone-working, and seal-cutting; the thread-maker’s spindle; the quern; and above all, the potter’s wheel.19 These provided the foundation for the earliest mechanized industries, and were steps toward the mass-production factories of the 20th century.
Materials development had an impact on culture in other ways than through the improvement of artifacts. This can perhaps best be seen in the development of writing. The growth of commerce and government stimulated the need for records. The materials to produce the records undoubtedly influenced the nature of the writing itself and, if modern linguistic scholars are correct, probably some details of the language structure and hence the mode of thought. Marshall McLuhan has popularized the phrase, “the medium is the message.” A painting, a poem, a print, a pot, a line of type, a ballet, a piece of carved sculpture, a hammered goldsmith’s work, or a TV image, all convey differences in sensory perceptions which form the basis of human communication,20 and we might guess that the same process occurred at the very beginning of art and purposeful records. The Sumerians in the Tigris-Euphrates valley had abundant clay to serve as their stationery, and the sharp stylus employed with it did not allow a cursive writing to develop; did this have some impact on the ways in which they thought, spoke, and acted? The Egyptions, on the other hand, could adapt the interwoven fibers of a reed growing in the Nile delta to produce a more flexible medium, papyrus, on which they could write with brushes and ink in less restricted ways. Thus, the differences between the cuneiform and hieroglyphic writing were dependent on the differences in materials available, quite as much as were the mud-brick and stone architecture of their respective regions. At the time, the visual arts were probably more significant than writing, for relatively few people, except professional scribes, would have been influenced by the latter. Certainly, our retrospective view of old civilizations depends on the preservation of art in material form, and the material embodiment of thought and symbol in the visual environment must have modified the experience and behavior of ancient peoples, even as it does today.
The replacement of copper and bronze by iron began about 1200 B.C. Iron had been produced long before then, because iron ores are prevalent and easily reduced at temperatures comparable to those required for smelting copper. However, the iron was probably not recognized as such, because at those temperatures it is not melted, but remains as a loose sponge of particles surrounded by slag and ash, being easily crumbled or pulverized and having no obvious metallic properties. If, on the other hand, the porous mass is hammered vigorously while hot, the particles weld together, the slag is forced out, and bars of wrought iron are produced.
Though metallic iron may have been previously seen as occasional lumpy by-products from lead and copper smelting (in which iron oxides were used to make siliceous impurities in the iron more fusible), its intentional smelting is commonly attributed to the Hittites, an Anatolian people, about 1500 B.C. The Hittite monopoly of ferrous knowledge was dispersed with the empire about 1200 B.C., but it took almost another 500 years before iron came into general use and displaced the mature metallurgy of bronze. Immense skill was needed to remove the oxygen in the ore by reaction with the charcoal fuel without allowing subsequent absorption of carbon to a point where the reduced metal became brittle. Moreover, each ore had its own problems with metalloid and rocky impurities.21
Certain forms of iron—those to which the name steel was once limited—can become intensely hard when heated red hot and quenched in water. This truly marvelous transmutation of properties must have been observed quite early, but its significance would have been hard to grasp and, in any case, it could not be put to use until some means of controlling the carbon content had been developed. Since the presence of carbon as the essential prerequisite was not known until the end of the 18th century A.D., good results were achieved only by a slowly-learned empirical rule-of-thumb schedule of the entire furnace regimen. Even the process of partial softening, today called tempering, was very late in appearing (perhaps in the 16th century) and early “tempering” was actually hardening done in a single quenching operation, in which the steel was withdrawn from the cooling bath at precisely the right moment. It is not surprising that this was rarely successful. Yet, even without hardening, iron had no difficulty in supplanting bronze for many applications. Its abundance meant that the elite could not control it. Iron was the “democratic” metal because a rise in the living standards among larger masses of population was obtainable through its application in tools and implements.22
The wide distribution of iron over the earth’s surface enabled it to serve for tools and agricultural implements as well as weapons of war and precious objects for the ruling households. Before 1,000 B.C., there are records of iron hoes, plowshares, sickles, and knives in use in Palestine. From about 700 B.C., iron axes came into play for clearing forest land in Europe and for agricultural purposes. Iron tools together with evolving organization arrangements greatly increased the productivity of agriculture, giving a surplus which could support large numbers of specialized craftsmen whose products, in turn, could become generally available instead of being monopolized by the wealthiest ruling circles. Furthermore, tools formerly made of bronze or stone—such as adzes, axes, chisels, drills, hammers, gravers, saws, gauges—could be made less expensively and more satisfactorily in iron. The new tools allowed for new methods of working materials: forging in dies, the stamping and punching of coins, and, many years later, developments such as the drawing of wire and the rolling of sheet and rod.
These metalworking methods were easily harnessed to water power when it appeared and opened up ways of making more serviceable and cheaper products. Though it was not immediately exploited, the strength of metals permitted the construction of delicate machines. Iron was at first used structurally only for reinforcing joints in stone or wood, but later its strength and stability were combined with precision in creating the modern machine tool, and its large-scale fabrication also made modern architecture possible.
MATERIALS IN CLASSICAL CIVILIZATION
It has been claimed that bronze made for the centralization of economic power as well as the concentration of political authority in the hands of an aristocratic few, while iron broadened the economic strength to a larger class of traders and craftsmen and so led to the decentralization of power and eventually to the formation of Athenian democracy.
Although the classical civilization of Greece rather fully exploited the possibilities offered by metals and other materials available to them from preceding ages, producing beautifully-wrought ceramics, exquisite jewelry, superb sculpture, and an architecture which still represents one of the peaks of the Western cultural and aesthetic tradition, they did little to innovate in the field of materials themselves.
The same is true of the Romans who acquired a great reputation as engineers, and rightly so, but this rests largely upon the monumental scale of their engineering endeavors—the great roads, aqueducts, and public structures—rather than upon any great mechanical innovations or the discovery of new materials.
There is one exception to this generalization. The Romans did introduce a new building material: hydraulic concrete. The use of lime mortar is extremely old, probably even preceding the firing of pottery, and lime plaster was used for floor and wall covering, for minor works of art and later for the lining of water reservoirs and channels. It can be made by firing limestone at a moderate red heat; it sets hard when mixed with water and allowed slowly to react with carbon dioxide in the air. If, however, the limestone contains alumina and silica (geologically from clay) and is fired at a higher temperature, a material of the class later to be called hydraulic, or Portland, cement is formed. After grinding and mixing with water, this sets by the crystallization of hydrated silicates even when air is excluded and develops high strength. The Romans were fortunate in having available large quantities of volcanic ash, pozzuolana, which, when mixed with lime, gave such a cement. They exploited it to extremely good purpose (reinforced with stone rubble or with hard bricks) in the construction of buildings, bridges, and aqueducts. Massive foundations and columns were much more easily built than with the older fitted-stone construction, and, unlike mortar, the cement was waterproof. By combining the new cement with the structural device of the arch, the Romans could roof-over large areas without the obstructions of columns.23
The case of hydraulic cement is representative of materials usage from antiquity until modern times. Namely, it was developed entirely on an empirical basis, without much in way of any science underlying the useful properties. The great Greek philosophers, to be sure, had worried about the nature of matter and the three states in which it exists—solid, liquid, and gas. These, indeed, constitute three of the four famous elements of Aristotle which dominated philosophy for nearly 2000 years. His earth, water, and air represent fine physical insight, but they had to be rejected by chemists in their search for compositional elements.24 But in any case, it was not philosophy that guided advance. The main contribution to early understanding came from the more intelligent empirical workers who discovered new materials, new reactions, and new types of behavior among the grand diversity of substances whose properties could be reproduced, but not explained except on an ad hoc basis. Through most of history, it has been the almost sensual experience with that complex aggregation of properties summed up in the term the “nature” of the material that has guided empirical search for new materials and modifications of old ones. The ability to go beyond such empiricism and to plan tests on the basis of an adequate theory of the composition-structure-property” relationships is a 20th century phenomenon and had to await the development of science. Moreover, the science needed was a kind that was slow to emerge because of the extreme complexity of the problems involved.
Unlike astronomy, there was little place for accurate measurements or geometry in materials, and those who sought to find rules were perpetually frustrated. The curious experimenter, however, by mixing, heating, and working materials in a myriad of ways did uncover virtually all of the materials with properties that were significant to him, namely, strength, malleability, corrosion resistance, color, texture, and fusibility. Science began to be helpful much later when chemical analysis—an outgrowth of the metallurgists’ methods of testing the metal content in ores before going to full-scale operation—advanced to the point where it showed that there were only a limited number of chemical elements and that ostensibly similar materials, differing in their nature, often contained different impurities. Then it was discovered that chemical substances of identical composition could differ in their internal structure, and finally structure became relatable to properties in a definite way; in fact, it was found possible to modify the structure purposefully to achieve a desired effect.25
There have been many interpretations of the decline and fall of the Great Roman Empire. The early Christian apologists claimed that Rome fell because it was wicked and immoral; in the 18th century, Gibbon blamed the fall of Rome upon Christianity itself. Since that time, the “fall” has been attributed to numerous factors: political, economic, military, cultural, and the like. It is not surprising, with the recent interest in the history of technology, that technological interpretations of Rome’s decline have begun to appear, and some
of these center on Rome’s use of materials, A few years ago, S.C.Gilfillan claimed that the decline of Rome was due to a decline in the birth rate of the Roman patrician class coming from dysgenic lead poisoning.26 Although all Romans got a goodly intake from their lead-lined water system, the elite drank more than its share of wine from lead vessels and this was thought to reduce the fertility of the leaders! Lately, a geochemist has claimed that Rome’s troubles derived from the economic effects of the enforced decline in silver production which began about 200 A.D. because the mines had become so deep that they could no longer be cleared of water with the technical means available.27
Throughout the first millennium after Christ, about the only places where ancient techniques of making and working materials underwent improvement were outside Europe—in the Arab World, Iran, India, and the Far East. Textiles, ceramics, articles in silver and bronze and iron of excellent quality appeared. That portentous new material, paper, originated in China and began its Western diffusion. Though the armorers of the Western world were steadily enhancing their products, the Crusaders of the 12th century had no steel which could match that of the Saracen sword. The Japanese sword surpassed the Islamic one by an even greater margin than the latter did the European. However, not for several centuries did these Oriental priorities in materials processing have any effect upon the materials science or technology of contemporary Western Christendom.
For all this, the first significant literature on materials is European—the Treatise on Divers Arts written about 1123, by a Benedictine monk under the pseudonym Theophilus.28 He was a practical metalworker and he described in full practical detail all the arts necessary for the embellishment of the church, such as the making of chalices, stained-glass windows, bells, organs, painted panels, and illuminated manuscripts.
Theophilus was no materials engineer in the modern sense, but he was a craftsman, probably, the historical goldsmith Roger of Helmarshausen, some of whose work has survived. His knowledge of matter was the directly-sensed, intuitive understanding that comes from constantly handling a wide variety of substances under different conditions. His Treatise is essentially a factual
“how-to” book, containing many exhortations to watch carefully for subtle changes in the materials being processed but with no trace of theoretical explanation. Theory does not appear in treatises intended to help the practical worker in materials until 600 years later—well into the 18th century.
Although the nature of materials themselves did not change greatly in Western Europe during the Middle Ages, a number of mechanical inventions facilitated both their production and their shaping.29 The first widespread application of power in processing materials was in grinding grain. This practice considerably increased when windpower supplemented the older waterpower, with the technique, as so much else, diffusing from the East. Textiles at first benefited only by the use of waterpower in the fulling process, but the mechanically simpler and more laborious metallurgical processes changed substantially. In ironworking, waterpower was applied successively to bellows, to hammers, and eventually (15th century) to slitting, rolling, and wire drawing.
A series of mechanical innovations and improvements led to advances in the manufacturing and processing of other materials, too. Plant ash to make glass was replaced by more-or-less pure soda, and the furnaces to melt it in became larger. Textile looms improved, especially with the introduction—from China—of the draw loom. Even more important was the development, near the close of the 13th century, of the spinning wheel, in place of the ancient handspun whorl, virtually unchanged since prehistoric times.
Power not only enabled the scale of operation to be increased in ironworking, but the product was more uniform because of the extensive working that was possible. In addition, the use of power changed the basic chemistry of the process. Although a large furnace is not needed in order to produce molten cast iron, it is much more easily made in a tall shaft furnace driven by powerful bellows than in a low hearth. Cast iron first appeared in Europe in the 14th century, following a sequence of developments which is unclear but which certainly involved power-driven bellows, larger furnaces, and perhaps hints from the East. To begin with, cast iron was used only as an intermediate stage in the making of steel or wrought iron, and it was developed for its efficiency in separating iron from the ore by production of liquid metal and slag. However, cast iron that contains enough carbon to be fusible is brittle, and it took Europeans some time to realize its utility, although it had long been used in the Far East.
By the beginning of the 15th century, cast iron containing about 3% carbon and commonly about 1% silicon and which melts at a temperature of about 1200° C in comparison with 1540° C for pure iron, had found three distinct uses—as a bath in which to immerse wrought iron in order to convert it into steel as a material to be cast in molds to produce objects like pots, fire irons, and fire backs more cheaply; and, most important of all, as the raw material for the next stage of iron manufacture.
The age-old process of directly smelting the ore with charcoal and flux
in an open hearth or low shaft furnace yielded a product of low-carbon material in the form of an unmelted spongy mass, which was forged to expel slag, to consolidate it, and shape it. It was inefficient because of the large amount of iron that remained in the slag, and the iron was defective because of the slag remaining in it. The wrought iron produced from cast iron by the new finery process was made by oxidizing the carbon and silicon in cast iron instead of by the direct reduction of the iron oxide ore. The two-stage indirect process gradually displaced the direct method in all technologically advanced countries. Its main justification was economic efficiency, for the resulting product was still wrought iron or steel, finished below its melting point and containing many internal inclusions of iron-silicate slag. In the late 18th century, the small hearth was replaced by a reverberatory puddling furnace which gave much larger output, but neither the chemistry nor the product was significantly different from that of the early finery.30
It was only with the possibility of obtaining temperatures high enough to melt low-carbon iron—essentially the time of Bessemer and Siemens in the 1860’s—that slag-free ductile iron became commercially possible. The very meaning of the word “steel” was changed in the process, for the word, previously restricted to quench-hardenable Medium- and high-carbon steel for tools, was appropriated by salesmen of the new product because of its implication of superiority.
The early developments in iron and steel metallurgy occurred with no assistance from theory, which, such as it was, was far behind practice. Medieval alchemists were not experimenting with cast iron because they felt they understood its chemistry, and they had not thought of its many potential uses.
The Aristotelean theory of matter, essentially unchallenged in Medieval times, recognized the solid, liquid, and gaseous states of matter in three of the four elements—the earth, water, air, and fire. The theory encompassed the various properties of materials but was wrong in attributing their origin to the combination of qualities rather than things. Medieval alchemists in their search for a relation between the qualities of matter and the principles of the universe elaborated this theory considerably. One of their goals—transmutation—was to change the association of qualities in natural bodies. In the days before the chemical elements had been identified, this was a perfectly sensible aim. What more proof of the validity of transmutation does one need than the change in quality of steel reproducibly accomplished by fire and water? Or the transmutation of ash and sand into a brilliant glass gem, and mud into a glorious Attic vase or Sung celadon pot? Or the conversion of copper into golden brass? Of course, today we know that it is impossible to duplicate simultaneously all the properties of gold in the absence of atomic nuclei having a positive charge 79. One way to secure a desired property is still to select the chemical entities involved but much can also be done by changing the structure of the substance. Modern alchemy is as much solid-state physics as it is chemistry, but it could not have appeared until chemists had unraveled the nature and number of the elements.
Urged on by the manifestly great changes of properties accompanying chemical operations, the alchemists worked on the same things that concerned the practical metallurgist, potter, and dyer of their day, but the two groups interacted not at all. In retrospect one can see that the alchemist’s concern with properties was not far from the motivation of the present-day materials scientist and engineer. They were right in believing that the property changes accompanying transmutation were manifestations of the primary principles of the universe, but they missed the significance of the underlying structure. Moreover, they overvalued a theory that was too ambitious, and so their literature is now of more value to students of psychology, mysticism, and art than it is a direct forerunner of modern science. Yet the alchemists discovered some important substances; they developed chemical apparatus and processes which are basic to science today, and they represented an important tradition of the theoretically-motivated experimentation, even if they failed to correct their theory by the results of well-planned critical experiments.31 This approach proved sterile during the Middle Ages, while the workshop tradition represented by Theophilus led to many advances. The collaboration between the two approaches, which is the very basis and principal characteristic of today’s emerging MSE was then impossible.
Two major technological developments helped precipitate the changes that signalized the close of the Middle Ages and the beginning of modern times: gun powder and printing. Both of these had earlier roots in Chinese technology and both were intimately related to materials.
In the case of printing,32 all the necessary separate elements were in general use in Western Europe by the middle of the 15th century; paper, presses, ink and, if not moveable type, at least wood-block printing of designs on textiles and pictures and text on paper, and separate punches to impress letters and words on coins and other metalwork. But, they had not been put together in Europe. Papyrus and parchment had been known in ancient times. Paper made of vegetable fiber had been invented in China a thousand years earlier and had been introduced into Spain by the Arabs during the 12th century. Simple presses were already in use for making wine and oil, while oil-based ink (another essential element in the printing process) had been developed by artists a short time previously.
The idea for the most important element needed for mass production of verbal communication—reusable individual type—probably came to Europe from the Orient, although the history is obscure. By the 11th century, Chinese printers were working with baked ceramic type mounted on a backing plate with an adhesive and removable for reuse. By the 14th century, in Korea, even
cast bronze type was known.
Shortly after 1440 in Europe, everything came together in an environment so receptive that the development was amost explosive. Though there may have been experiments in the Lowlands, the successful combination of all the factors occurred in Mainz in Germany, where Johann Gutenberg began experiments in the casting of metal type during the 1440’s. By 1455 he and his associates were able to produce a magnificent book, the “Gutenberg Bible,” still one of the finest examples of European printing. It consists of 643 leaves, about 40 × 29 cm in size, printed on both sides with gothic type in two columns. Some chapter headings were printed in red, others inserted by hand. Part of the edition was printed on paper, part on vellum, the traditional material for permanence or prestige. Unlike the earlier Oriental type, Gutenberg’s was cast in a metal mold having a replacable matrix with a stamped impression of the letter, arranged so that the body of the type was exactly rectangular and would lock firmly together line-by-line within the form for each page. Both the metal and the mold were adopted from the pewterer’s practice. Thus, a new technique for mass production and communication was established, ushering in a potential instrument for mass education. Modern times were beginning.
The political and economic environment had been strongly influenced somewhat earlier by the introduction of gunpowder in Western Europe. Explosive mixtures for holiday firecrackers had been used for centuries in China; it was only in the “civilized” West that gunpowder was first employed to enable man to kill his fellowman. Here, too, it is uncertain whether introduction of gunpowder in the West was a result of independent discovery or diffusion from the Far East. At any rate, the application and development was different and prompt. As early as 1325, primitive cannon were built in the West for throwing darts, arrows, and heavy stone balls, in competition with the mechanical artillery (the ballista) familiar since the days of the Romans, which were displaced completely by the middle of the 16th century. By 1450, the musket had appeared, and began to render the cross-bow and long-bow obsolete.
By 1500, bombards, mortars, and explosive mines caused the medieval elements of warfare—the fortified castle and the individual armored knight—to lose their military importance, and contributed to the decline of the feudal nobility.33 (Another technical device—the stirrup, had aided their rise.)34 Accordingly, the changes in the technology of warfare aided in the process of administrative and territorial consolidation which was to give birth to the national state and transform the map of Europe.
Even the layout of cities changed as a result of the new methods of warfare: the round towers and high straight walls no longer afforded good defense in the age of cannon; they were replaced by geometrically-planned walls and arranged so that every face could be enfiladed.
Military needs sparked a great development in the scale of the material-producing industries during the Renaissance, but agriculture, construction, and the generally rising standard of living also contributed and benefited. The new supply of silver coming from Spanish operations in the New World and, no less, from the development of the liquation process for recovering silver from copper upset the monetary balance of Europe. Silver, pewter, wood, and the greatly-increased production of glazed ceramic vied with each other for domestic attention, and glass democratically appeared in more windows and on more tables.
We know much more about material-producing processes in the 16th century than we do of earler ages, because the printing press gave a wider audience and made it worthwhile for men to write down the details of their craft in order to instruct others rather than to keep their trade secrets. Some of our most famous treatises on materials technology date from the 16th century, and the best of these continued to be reprinted over 150 years later—an indication that practices were not advancing rapidly.
The most famous of these treatises is the de Re Metallica35 by Georg Bauer (Latin, Georgius Agricola) published posthumously in 1556. Agricola was a highly literate and intellectually curious physician living in Bohemian Joachimstal and Silesian Chemnitz, both mining and smelting towns, and his systematic factual descriptions of minerals, mining, and smelting operations, all excellently illustrated, shed much light on the devices and techniques of the times. Agricola writes of large-scale industrial operations, with a center of interest far removed from the craftsman’s workship by Theophilus centuries earlier. The scale is that of a capitalistic enterprise. Nevertheless, Agricola still thought in the same terms as did Theophilus; his de Re Metallica is simply a description of actual practice, devoid of any theoretical principles, though in other works he did speculate fruitfully on the nature and origin of minerals.
Sixteen years earlier, the Italian foundryman Vannoccio Biringuccio had published his de 1a Pirotechnia, which is much broader in scope.36 It has less detail on the smelting operations, but is excellent on all aspects of casting and working metals and has good discussions of glassmaking, smithy operations, the casting of bells, and especially the manufacture of cannon and gunpowder. He says that the bronze founder looks like a chimney sweep, is in perpetual danger of a fatal accident and fearful of the outcome of each casting, is regarded as a fool by his countryment, “but with all this it is a profitable and skilled art and in large part delightful.” Biringuccio says that fortune will favor you if you take proper precautions in doing your work in the foundry, and he advocates the empirical approach, almost as a modern experimentalist, in these words, “It is necessary to find the true method by doing it again and again, always varying the procedure and then stopping at the best.” His section on casting, boring, and mounting of cannon is specially good, and shows
how dependent all this was on the earlier technique of the bell founder, which he also meticulously reports.
Both Agricola and Biringuccio describe the quantitative analytical methods for assaying ores and metallurgical products. Even better on this aspect of chemistry is the great treatise of Lazarus Ercker, the Beschreibung allerfürnemisten mineralischen Ertzt und Bergwercksarten, published in Prague in 1574.37 Ercker’s exposition of the assayer’s art displays intimate knowledge of the reactions, miscibilities, and separations of the common metals and oxides, sulfides, slags, and fluxes as well as sophisticated methods of cupelling, parting with acid, etc., and is thoroughly quantitative in outlook and intent.
In all these early writings, there is a strong bias toward the precious metals, gold and silver. Even Biringuccio, who was concerned with end-use far more than other writers, had very little to say about iron despite the fact that this was the most common metal then, as now. The rough labor of the smith was almost beneath the notice of educated men. There is no comprehensive book devoted to iron until that of R.A.F.de Réaumur published in 1722.38 This was preceded only by an anonymous little treatise on the hardening and etching of iron (1532), a Polish poem of 1612 (The Officina Ferraria by W.Rozdienski) and a fine description of locksmiths’ and skilled ironworkers’ operations by Mathurin Jouse in 1627.39 Though glass is treated in fair detail by Biringuccio, the first book devoted entirely to it is that by Neri in 1612.
Other practical arts gradually received a place in the visible literature. Piccolpasso’s unpublished manuscript of 1550 has fine detail on all stages of ceramic manufacture, glazing, and decoration.40 The Plictho of Fioventura Rosetti (1548) has descriptions on dyeing.41 Other booklets give innumerable recipes for the making of ink, soldering, gilding, removing spots, along with many cosmetic and household craft recipes.42 The sudden appearance of this literature in print does not mean that the processes described were new in the 16th century; indeed, most of them had been going around for centuries, circulated by word-of-mouth or in rough manuscripts of a form and content that no literary custodian would think worth keeping.
If in this treatment we seem to have overemphasized the 16th century, it is because intimate records become available for the first time of techniques built upon many centuries of slow consolidation of changes. These writings show vividly how much can be done without the benefit of science, but at their own times they served to disseminate to a large and new audience knowledge of the way materials behaved; such knowledge was an essential basis for later scientific attack.
With the exception of Agricola, all of this literature was written in the vernacular tongue, Italian, French, or German. It was part of the Reformation. Instead of theoretical dogma handed down from on high for intellectual gratification, it was down-to-earth practical information for the workshop and kitchen. The realization that theory could help this kind of practice was quite slow in emerging, and a real science of materials had to wait for another two centuries. In the meantime, the separate components of ferrous and nonferrous metallurgy, ceramics, dyeing, fiber technology, organic polymers, and structural engineering pursued their own separate lines of development, and the basic sciences of chemistry and physics slowly generated an understanding that would help explain practice, enrich, and extend it. Together, this all served to provide the facts and viewpoints that would eventually knit into the new grouping of man’s knowledge and activity known as materials science and engineering.
THE START OF A SCIENTIFIC MATERIALS TECHNOLOGY BASED ON CHEMISTRY
The linking of theoretical understanding with practical applications, the hallmark of MSE, did not occur with the Scientific Revolution of the 17th century nor the Industrial Revolution of the 18th and 19th centuries. Tremendous advances occurred during the 17th to 19th centuries in scientific understanding of the nature and operation of the physical universe at both atomic and cosmic levels, but very little of this could find direct connection to the materials made and used by man. Although major transformations were taking place in the processing and application of old materials, and new ones were being developed, these were largely the product of empirical advances within materials technology itself, owing little to contemporary scientific understanding.
Indeed, the very complicated origins of the useful properties of materials precluded understanding by the necessarily simplistic methods of rigorous science. Though kinetics and elasticity were simple enough to be handled by the new mathematics, the mechanics of plasticity and fracture were utterly beyond it. Unsuspected variations in composition and structure produced changes in properties that could be manipulated only by those who enjoyed messy reality. Science could advance only by ignoring these problems and finding others in which it was possible, both theoretically and experimentally, to exclude unknown, unwanted, or uncontrollable variables.
Eventually, of course, on the fragmentary knowledge so acquired, it became possible to deal with real materials, but those properties that are structure-sensitive—which includes most of the interesting properties of
matter from the user’s viewpoint—have been very late in succumbing. It would surely have delayed understanding had some superpower insisted that physicists work upon important but insolvable (at that time) properties of matter. Materials practitioners cannot disregard those aspects of the behavior of matter simply because a scientist cannot deal with them. The development of the different threads of knowledge proceeds each at its own pace. Every scientific concept has come about from an analytical understanding of only a part, albeit often the central part, of a real complex phenomenon. The approach usually requires a temporary blindness to some aspect of the rich behavior of nature, which stimulated the study in the beginning. A price is paid for each step in understanding. Eventually, however, the excluded aspects, at least if they are real, can be included in a higher synthesis. However, the history of MSE shows that this synthesis is more than the putting together of exact understanding of many parts; it is putting this understanding into a higher, or at least broader, framework which combines experience as well as logic. All levels, all viewpoints must interact and the present tension between the different parts of the materials profession gives ground for hope that new methods of managing this difficult synthesis are beginning to emerge. It is rare for both attitudes of mind to be combined in one individual, but a tolerance indeed an enjoyment, of opposing points-of-view is one of the things that makes MSE so interesting today.
In the past, even when breakthroughs occurred which might have illumined the nature and structure of materials, their significance was not immediately apparent to the practitioner and the impact on technology was delayed. With only a few exceptions, the coupling of science to engineering had to await the slow development of new concepts, a tolerance for new approaches, and the establishment of new institutions to create a hybrid form: engineering science, or, if one prefers, scientific technology—which is basically different from both the older handbook-using technology and rigorous exclusive science.43 This is mainly a 20th-century, even a mid-20th-century, development.
With hindsight, we can see how scientific advances of earlier times could have been adopted by contemporary engineers more promptly than they actually were. Nevertheless, a practical metallurgist or potter quite rightly disregarded the theoretical chemistry of 1600 A.D. as well as the physicist’s ideas on matter in 1900 A.D. Both would have been quite useless to him. Yet, with the passing of time, these inapplicable approaches developed to the point where many new advances stemmed from them. We can equally wonder why scientists were frequently so obtuse as to make no attempt to investigate or to comprehend the fascinating complex problems which arose in practice. Such an approach would have been completely a-historical. It would ignore the fact that the implications of new viewpoints tend not to be apparent to men whose practice and whose ideas are in productive harmony at the time; it would also ignore the fact that science and technology had developed out of different traditions—the philosophic and scholarly on one hand, the art and craft and oral tradition on the other. A major reshuffling of attitudes and institutional devices was essential before the two could be brought together in a
fruitful relationship; what is more, science and technology had to advance, each in its own way, to the point where they addressed themselves to common problems.
Science arose from a kind of union between philosophy and technology, but it was only when both science and technology had each reached a high level of development that continued progress became difficult without concomitant advances in the other. It was then recognized that their unified actions were mutually beneficial, and of service to mankind.
If we outline briefly the developments in materials science and in materials engineering during the 18th and 19th centuries, we can see some hints of the eventual emergence of the new and fruitful relationship to which we have given the name of “scientific technology.”
The story of sal ammoniac in the 18th century is instructive in this regard. Robert T.Multhauf has shown how virtually all of the chemical data needed in the various processes for producing sal ammoniac can be found in the scientific literature prior to the effective foundation of European industry. But it is difficult to prove how, if at all, the scientific knowledge was actually transmitted to the manufacturer who had to design large-scale, safe, and economical equipment, conceive of interdependent processes using the byproducts, and build the factories producing not just one but many marketable chemicals. As Multhauf states, “it seems very probable that the obscure men who were primarily responsible for the success of that industry were beneficiaries of the literature of popular science which flourished in the mid-18th century. But if the technology of sal ammoniac was ultimately dependent upon science, the scientists played a very minor role in the industrialization of sal ammoniac production, which was accomplished primarily by men whose principal qualifications seemed to have been ingenuity and a spirit of enterprise.”44
The great technological feats of the mid-18th century—the hallmark inventions of the Industrial Revolution—came from men without formal training in science. The mechanicians who produced them, such as James Watt, were not unlettered men, and were not ignorant of the empirical science which they needed for their technical work, but this was not paced by new research at the scientific frontier.45 James Watt did have contact with Dr. Joseph Black, the discoverer of latent and specific heat, but if Watt should share credit with anybody, it would be Matthew Boulton, the entrepreneur, rather than Joseph Black, the scientist.
This does not mean that there was no interplay between science and technology during this early period, nor that such contacts were not fruitful. Indeed, we have some very notable exceptions which prove the rule. For example, the need for bleaching and dyeing textiles and for porcelain to compete with the superb imports from the Far East stimulated basic investigations in high-temperature and analytical chemistry; a virtually direct line
can be traced from these technical needs to the discovery of oxygen and the definition of a chemical element which was to be the basis of the Chemical Revolution of the late 18th century. The classic examples for close relationship between science and technology in the 19th century were thermodynamics and electricity. In the former case, technology presented problems for science; in the latter, science presented potentialities for technology. But beyond these simple connections, what were the customary relationships between science and technology, the interactions as well as the reactions?
Men like Carnot and Edouard Seguin, who were responsible for primary theoretical advances in the field of thermodynamics, were engineers by profession. In his investigation of energy, James Prescott Joule always started with some specific technical problem, for example, the practical performance of an electrical motor with its production of work and heat. There is no doubt that the engine—the steam engine, and later the internal-combustion engine and the electric motor—presented problems which attracted the attention of scientists, and led to theoretical developments. But—and this is perhaps the crucial point—although technological advances spurred advances in theory, the theoretical knowledge obtained with such stimuli was very slow to feed back to technology.
Lynwood Bryant has shown, as a case in point, that the important steps in the development of the heat engine came from practical men not very close to theory, and the academicians, who understood the theory, did not invent the engine. Despite this, the change from the common-sense criteria of fuel economy to a new criterion of thermal efficiency marked a step toward the domain of abstractions, of invisible things like heat and energy, and was a major development in bringing scientific technology into being.46
The discovery of voltaic electricity as a result of the work by Galvani and Volta in 1791 to 1800 initiated a totally new period in the relationship between science and technology. Discovered in the laboratory, electricity inspired a number of empirical experimenters and gadgeteers but it found no practical use for nearly forty years, when the electric telegraph and electroplating appeared almost simultaneously. These applications provided an opportunity for many people of different intellectual and practical approaches to acquire experience with the new force.47 The beginning of the electrical power industry lies in the design of generators for the electroplater, and widespread knowledge of circuitry came from the electric telegraph. From our viewpoint, it should be noted that electrical science and industry both required the measurement of new properties of matter. Conductors and insulators were, of course, well known and classified. The relationship between thermal and electrical conductivity had been identified and some studies of the
magnetic properties of the simple materials had been carried out well before 1800, but the richness of the field appeared only when experiments done in connection with the first Atlantic cable showed the great differences in the conductivity of copper from different sources and eventually related conductivity to the nature of the alloy. With the transformer came studies of iron alloys in the search for lower hysteresis losses, and the science and practice never thereafter parted company.
Up to this point, virtually all interest in the properties of materials was related to their mechanical properties along with reasonable resistance to corrosion. Even in the electrical areas, however, improvements and applications continued to come from the technology more than the science. Edison, the greatest electrical inventor of the century, was not schooled in electrical science and sometimes did things opposed to electrical theory. In Kelvin, we see a man of the future, but even he did not let his theory restrain his empirical genius. Well into the 20th century, men in close practical contact with the properties of materials had a better intuitive grasp of the behavior of matter than did well-established scientists.
The mutually reinforcing attitudes of mind which eventually led men to associate in MSE at first led technologists and scientists to place emphasis on different facets of the same totality of knowledge and experience. Scientists, in the simplifications that are essential to them, must often leave out some aspect which the technologist cannot ignore, and they usually overemphasize those aspects of nature that are newly discovered. It is commonplace to ridicule outmoded theories after new viewpoints have shown their strength. Yet, it can be claimed that the relegation of phlogiston to the dustbin of history by the 18th century chemists was something of a loss, for the properties of metals are indeed due to a nearly intangible metallizing principle—the valence electron in the conduction band in today’s quantum theory of the metallic state. Similarly, the success of Dalton’s atomic theory drew attention away from compounds that did not have simple combining proportions, and it left the very exciting properties of non-stoichiometric compounds to be rediscovered in the middle of the 20th century. Lavoisier’s enthusiasm for the newly-discovered oxygen not only led him to believe it to be the basis of all acids—hence its name—but also to claim that its presence was responsible for the properties of white cast iron. Both were errors which took some years to eradicate.
Chemistry at the end of the 18th century turned away completely from the old concern with qualities and adapted a purely compositional and analytical approach to materials. This was an approach with which something clearly worthwhile could be done, whereas properties (being structure-sensitive as we now know) could only be handled individually by purely ad-hoc suppositions regarding the parts or corpuscles, which the ill-fated Cartesian viewpoint had made briefly popular. From analytical chemistry came a major triumph; new quantitative concepts of elements and atoms and molecules. These remain an essential basis of MSE although the control of composition is now seen less as an end in itself as an easy or cheap way of obtaining a desired structure.
The discovery of the presence of carbon and its chemical role in steel was a great achievement of 18th-century analytical chemistry. Indeed, until that time ignorance regarding chemical composition meant that there could be
little basic conception of the nature of steel, and hence there was much confusion regarding both its definition and its production. A full understanding of the changes in the properties of steel on hardening could not be reached until it was learned in 1774–1781 that the carbon which helped produce the fire also entered into the makeup of the steel itself.48
The obvious value of this and related chemical knowledge eventually brought chemists as analysts into every large industrial establishment, but it also led to a temporary disregard of some promising earlier work on structure, which had begun by observations on the fracture appearance of bellmetal, steel, and other materials. The fracture test is extremely old and artisans to this day often judge the quality of their materials from the characteristic texture and color of broken surfaces. Early in the 18th century, the versatile scientist de Réaumur applied quite sound structural concepts to the making and hardening of steel and malleable cast iron, as well as to porcelain. He had interests ranging all the way from advanced science to traditional practice, and he carried out much of his work specifically for the purpose of reducing the cost of materials so that the common man could enjoy beautiful objects. Réaumur was the very model of a modern material scientist and engineer.49 He had virtually no followers, for the leading physicists became increasingly absorbed by mathematical science under the influence of Newton and they joined the chemists who were proud of having thrown over the ancient intangible “qualities” for the new analytical approach.
The only scientific interest in the structure of matter at the end of the 18th century existed in the field of crystallography applied to the identification and classification of minerals. Some superb mathematics was developed around the concept of stacking among perfect crystalline polyhedra, but it failed to connect in any effective way with atomic theory, and few people even suspected that most real materials were composed of hosts of tiny imperfect crystals.
As a result, Réaumur’s approach, which would have been fertile in the thought and practice of metallurgy had it been followed up, lay fallow for over a century—until Henry Clifton Sorby applied the microscope to steel (1863) and discovered that the grains which could be seen on a fractured surface were actually crystalline in nature and changed in response to composition and heat treatment. But even then, it was to take another two decades before the full significance of Sorby’s discovery was recognized, when other metallurgists and engineers began to focus their attention on structure as well as composition.50
Yet these great strides in the fundamental understanding of the nature of metals and alloys occurred independently of—and indeed almost oblivious to—contemporaneous advances in practical metallurgy. While the chemistry of steel was being developed in Sweden and France, practical innovations in furnace design and operation and new methods of refining, consolidating, and
and shaping wrought iron appeared in England. All this came about entirely without benefit of science, and yet it was a major factor in the social and economic changes referred to as the Industrial Revolution.
A major step in increasing the production of iron and decreasing its cost was Abraham Darby’s solution, in 1709, of the problem that had been worked on for centuries, that of using abundant coal instead of charcoal for smelting purposes. This he did by coking the coal, removing volatile hydrocarbons and sulphur. Charcoal was in short supply and expensive, because of previous deforestation caused both by the needs of smelting itself and to provide land for agriculture. Darby’s discovery was based more on a happy accident of nature than any scientific formulations, for both the ore and the coal available in Coalbrookdale, where Darby’s iron works existed, were unusually low in the harmful impurities, sulphur and phosphorus.
Equally important was Henry Cort’s improvement of the production of wrought iron. He developed the puddling process in which coke-smelted pig iron was oxidized on a large scale in reverberatory furnaces instead of in small batches in the earlier firing hearths, and he combined this with the rolling mill to give an integrated plant for the large-scale, low-cost production of bar iron in a diversity of shapes and sizes. This was in 1784 and it is rightly regarded as one of the chief contributors to the rapid development of industry and changing attitudes in the Industrial Revolution.51 At about the same time, the English pottery industry was changing its scale and nature, partly because of new compositions and partly by more consciously applying new chemical knowledge and management techniques. In this, Josiah Wedgwood was an outstanding leader, though he undoubtedly got some inspiration from the scientific work on the continent and reports of the mass production techniques in the great Chinese factories. But, of course, the iron and pottery industries were only one part of a much broader organic change involving marketing techniques (in which Wedgwood himself was a pioneer), transportation with the expanding canal system, power becoming geographically unrestricted through the advent of the steam engine, a new sense of urbanization, and a growing middle class.
The next radical change in the iron industry was the making of low-carbon steels in the molten state. Before the 1860’s, malleable iron had perforce always been consolidated at temperatures below its melting point, with inevitable heterogeneity in carbon content and entrapment of slag and other inclusions. Tool steel containing about 1 percent carbon had been made by melting “blister steel” in a crucible and casting into ingots from about 1740, but temperatures high enough to melt the low-carbon materials had to await, first, the discovery by Henry Bessemer in England (or William Kelly in America) that the oxidation of the impurities in the pig iron would themselves provide enough heat to melt pure iron and, second, (perhaps more important for a century, though much less in the public eye) the development of the efficient open hearth furnace by the Siemens brothers and its adaptation to steelmaking
by melting pig iron and ore together, or pig iron and scrap—the latter by the Martins in France.52
Though he implies otherwise in his autobiography53, Bessemer did not come to his process through a study of new chemical and physical discoveries. He happened to see the unmelted shell of a pig of cast iron that had been exposed to air while being melted in a reverbatory furnace, and this started him thinking about oxidation. The thermal aspect of his process was also not anticipated, and his first experiments on blowing air through molten cast iron were done in crucibles set into furnaces to provide enough external heat. But, of course, he knew enough schoolboy chemistry and physics to realize the significance of what he observed, and had the energy needed to develop the process from an observation to a commercial success. His converter became almost a symbol of an age.
Like Darby, however, Bessemer was also the beneficiary of a happy environmental accident. He had ordered some pig iron from a local merchant without any specification, and it just happened to be unusually low in sulphur and phosphorus. His first licensees, using a poorer quality of iron, could not produce good steel; he bought back the contracts and employed some first-rate analytical chemists who found out what the trouble was. Moreover, even the best available iron had some residual sulphur which made the metal “hot-short,” i.e., fragile when hot. This, in turn, was corrected by the addition of manganese which had previously been used in crucible-melted steels but (as Robert Mushet who patented it recognized) it was particularly useful in “pneumatic steel” for correcting the effect of oxygen as well as sulphur. When added as high-carbon spiegeleisen, the ferroalloy simultaneously restored the burnt-out carbon to the level desired in the finished steel. None of these represented advanced scientific concepts at the time, yet all would have evolved far more slowly without the foundation of chemical understanding that came out of the 18th century.
The open hearth furnace was a direct result of new thermodynamic thinking, as was the related Cowper stove for efficiently heating the air for the blast furnace, although the invention of the hot blast itself had occurred in 1828 on the basis of a practical hunch. The Martin process was first simply used for melting and was advantageous in that it employed scrap, but combined with Siemens original plan to melt pig iron and ore in refining, it achieved great flexibility. Neither the converter nor the open hearth process could remove phosphorus; although an oxidizing slag in the presence of the lime can remove phosphorus, its use was impractical until a refractory for lining the furnace could be found that would withstand the corrosive effect of such a slag at the high temperatures involved. The Thomas invention of the basic process using magnesite or dolomite solved this—and changed the industrial map of Europe. This illustrates the intimate relationship between metallurgy and ceramics; all metallurgical processes are dependent upon the availability of materials to contain them.
The 19th-century developments in metallurgy almost all aimed at the more efficient production of materials known for centuries. Chemical theory was helpful to guide improvements, and chemical analysis became essential in the control of both raw materials and processes. By the end of the 19th century, most major metallurgical works had their chemical laboratories, and it was through the analytical chemist that a scientific viewpoint found its way into the industry. Moreover, a new outlook on the part of the metallurgist was beginning to take form, by the comination of the engineer’s concern with properties, the microscopist’s new knowledge of structure, and a flurry of new empirical alloy compositions inspired by the increasing demands of the mechanical engineer.
The accidental discovery of age hardening in aluminum alloys in 1906 led to the zeppelin (with great psychological if not military effect in World War I) and turned metallurgical thought to a new field, dispersion hardening, of great practical importance and even greater theoretical significance.54 More than anything else, this event revealed the richness of structure on a scale between the atom and the crystal and stimulated studies of composite materials of all kinds. Previously, the main metallurgical advances lay in the development of alloy steels. This had become a purposeful objective at the end of the 19th century, for most earlier attempts to improve steel had involved relatively small pieces of metal for cutting tools in which only hardness and wear resistance were needed. Today’s alloy steels, of course, are those in which high strength and reasonable ductility are required throughout the entire section of relatively large machine components or structures, and the role of the alloy is more to control the depth to which quench-hardening is effective than it is to obtain higher hardness. The industrial use of modern alloy steels starts with Hadfield’s high-manganese steel of 1882, soon followed by nickel steels in 1889 (at first for armament) and vanadium steels in 1904. The last were invented in France, improved in England, but most widely used in the United States—by Henry Ford. The requirements of the automobile were the principal incentive for the large-scale development of alloy steels, but the studies of them, at first largely empirical, profoundly influenced the growing science of metals by forcing attention to the complicated structural changes that occur during heat treatment.
Changes of materials can interact with society in ever-widening and often invisible ways. The entree of alloy steels that underlay the automobile and the change in suburban life that came with it is simply one example of the process. A century earlier the whole rhythm of life had been profoundly affected by improved methods of lighting; later came the refractory thoria mantle for the incandescent gas light, which was in turn largely replaced by the incandescent electric lamp; the latter became possible after a search for filament material had yielded first carbon, then tantalum, and finally, drawn tungsten wire of controlled grain size and shape. The incandescent lamp itself has been partly supplanted by fluorescent lamps depending on materials of quite different physics; still more recently lamps using high-pressure sodium vapor in alumina envelopes, resulting from the most advanced ceramic technology, altered the patterns of crime on city streets.
The development of cutting tools as part of the background of steel technology was mentioned previously. Tools, however, react significantly on all methods of production and even on the selection and design of whatever is being produced. For cutting operations performed by hand the traditional carbon steel, hardened by quenching and tempering, was adequate. In the middle of the 18th century, the uniformity of carbon steel (though not its quality) was considerably improved by the introduction of Huntsman’s method of melting and casting it. His “crucible” steel was originally intended as a better material for watch springs, but once the smiths and toolmakers learned to work with it, it slowly displaced the unmelted steels for most exacting cutting applications. However, such tool steel softens at about 250° C and this temperature was easily reached at the tips of tools in power-driven lathes. Experiments to improve steel by alloying (including some notable experiments by the eminent Faraday in 1819) showed little advantage and did not disclose the greater depth of hardening in alloy steels which today is the major reason for using them. However, this line, beginning with naval armor plate in the 1880’s, became industrially important to automobile manufacture around 1900.
Tungsten had been introduced into tool steels by Robert Mushet in 1868. His tool steel contained 9% tungsten and, when given a normal heat treatment, was found to wear much better than ordinary steel. Its use was economical because it needed less frequent grinding, but it did not produce any drastic change in the machine-tool industry. Then, in 1898, Taylor and White who were systematically studying the factors that affected machine-shop productivity, discovered that an enormous improvement could be derived from quenching a high tungsten steel from a very high temperature. Such steels were able to cut at much higher temperatures than ever before and the lathe was completely redesigned to stand the higher stresses resulting from the removal of metal at a faster rate. An even more spectacular change arose from the introduction of the sintered tungsten carbide tools in the early 1920’s. In turn, this intensified scientific interest in sintering mechanisms, and an important new industry came into being—that of powder-metal fabrication (previously only used for tungsten lamp filaments). Yet, the consuming public sees such major advances only in the lower cost or higher precision of the final product.
The age-old abrasive shaping process was revolutionized at about the same time as metal cutting. Synthetic abrasives began with silicon carbide as a product of the electric furnace in 1891, culminating in synthetic diamond (which became commercial in the 1960’s) and most recently boron nitrides. Modern mass production of precision parts would have been quite impossible without silicon carbide and related materials for grinding wheels, and the new generation of machines that utilize them.
THE NEW SCIENCE OF MATERIALS BASED ON STRUCTURE
Modern MSE, however, involves much more than metals. Perhaps the most dramatic changes in this century have been in organic materials, and for this we must return to the 19th century and the development of organic chemistry, moving from the simple inorganic molecule of Dalton into molecules of far more complicated structure. Simple atomic properties beautifully explained the composition of homologous series of compounds such as the aliphatic hydrocarbons. Then the fact that organic substances of the same composition could
have vastly different properties—isomerism—forced attention to a richer molecular structure, though similar phenomena had been known much earlier in connection with elemental sulphur and carbon. Wöhler’s synthesis of urea from inorganic compounds in 1828 was the first visible step to the union of the organic and inorganic worlds in chemistry, but it took a century and a half more before they merged via structure into a common science of materials. The isomerism of tartrates and racemates was discovered by Berzelius in 1830, and Pasteur showed, in 1848, that when crystallized the latter gave two crystal forms that were mirror images of each other and opposite in optical activity.55
The structure of molecules took on added meaning when the German chemist Kelulé saw that chemical formulae could designate or even model specific arrangements of atoms in the make-up of the molecule, instead of simply listing the number of atoms of each element.56 His structural formulae for designating the associations of individual atoms in organic compounds gave a precise representation of the molecule. His flash of insight in seeing the ring structure of the benzene-molecule as distinct from the linear-chain character of the aliphatic hydrocarbon molecules not only served to distinguish these two great classes of compounds, but it provided a basic concept for understanding the nature of polymers which are so important today. In retrospect, it is curious that the 19th-century chemists tended to resist the idea that their formulae represented the real structure of their molecules: this approach was regarded as little more than a notational device. Only toward the end of the century did levels of aggregation beyond that of the simplest molecule begin to be of concern to scientists, and not until those who were concerned with structure at any level were ready to join with others could modern MSE begin.
Kekulé’s benzene ring diagram soon had application in industry. Just a few years earlier, in 1856, a young British chemist, W.H.Perkin, attempting to make quinine artificially in a laboratory, discovered a purple dye which he named “mauve.” This was the first of the synthetic aniline dyes, and represented the beginning of the coal-tar chemical industry. The benzene ring diagram showed the structural nature of these organic molecules, and provided guidelines for the discovery and synthesis of new ones. Under the stimulus of Perkin’s discovery and others, the natural dyes, such as indigo, were soon replaced by synthetic ones. In the synthetic dye industry, as elaborated in Germany during the last half of the 19th century, we can see a prototype of what was to become one of the basic elements in MSE, namely, the coupling together of theory and practice, basic research done with an end-use clearly in mind. Although the first aniline dye had been discovered in Britain, it was in Germany that research chemists worked in laboratories which were attached to—indeed, were an integral part of—industrial chemical works.57
The primacy of the German chemical industry from the last quarter of the 19th century through World War II was undoubtedly a direct result of this fruitful coupling of research with production, and the converse effect of industrial activity on the liveliness of the academic laboratories can also be seen. The German dye industry is an early example of the fruitful interaction between laboratory and factory which was later to become one of the major prerequisites of MSE.
Eventually, from this approach, came whole new classes of synthetic organic materials: the plastics. Modern plastics date essentially from the development of Leo Baekland, in 1909, of phenol-formaldehyde compositions which can be molded into any shape and hardened through molecular cross-linking by heating under pressure. This precipitated an active period of scientific study of the synthesis and behavior of large molecules (both aiding and and being aided by biochemical studies of proteins) and gave rise to the industrial development of inexpensive easily fabricated materials for general use as well as many specially tailored materials in which desirable properties could be uniquely combined. There was, however, a prehistory of polymers in both the technology and science before Baekland’s great discovery.
Polymers based on natural products had been used for millennia in the form of lacquer. Many of these were combined with other substances to reinforce them or to change their properties as in today’s composite materials. Natural polymers such as ivory, tortoise shell, and bone had been artificially shaped under heat and pressure molding, and rubber had been used in fabrics of various kinds. None, however, was industrially important until the development of the vulcanization process in 1841. Vulcanized rubber and the heat-moldable natural resin from Malaysia called gutta-percha were extensively used as insulators in electrical apparatus. The first moldable totally-artificial plastic material was celluloid (nitrocellulose and camphor) first used for pretty trinkets but soon for shirt collars and eventually photographic films and numerous other objects such as batter cases. It was, however, dangerously inflammable. Synthetic fibers did not become commercial until the advent of cellulose acetate, “artificial silk,” in the 1920’s.58
The background of artificial organic materials in the form of fibers reaches back to suggestions of the great scientists Robert Hooke and R.A.F. de Réaumur in 1665 and 1710 respectively, but this did not bear fruit until the 1850’s when nitrocellulose was extruded into fine threads, already called “artificial silk.” Joseph Swan’s work on the development of carbon filaments for electric lamps led him to make fabrics from artificial fibers in the 1880’s, but commercial production stems from France. Other means of getting natural cellulose into fibrous form was via solution in alkaline copper solutions—a process in connection with which stretch spinning was first used, thereby permitting the formation of very fine fibers with oriented molecules—the cellulose acetate process; and the viscose process, in which cellulose was put into solution with alkali and carbon bisulfide. The last was for years the most popular, but in the late 1940’s cellulose-based processes were largely displaced by the introduction of synthetic polymer fibers. All these processes were used for other than textile purposes, notably the
cellulose acetate airplane-wing “doping” and the base for photographic film. These developments gave the organic chemists and manufacturers experience with polymers, and the public acceptance of pleasant, low-cost garments made of “rayon” laid the ground for widespread acceptance of plastic products in general. Synthetic resins came into wide usage for reinforcing viscose fibers and improving the surface characteristics of fabrics.
The underlying chemistry and physics of polymers unfolded without much connection with the older inorganic material sciences. It seems certain, however, that in the future, the basic sciences of metals, ceramics, and organic materials will mutually enrich one another, no matter how diverse the manufacturing industries may remain. Emulating the earlier German chemical industry, scientists and engineers in the American plastics industry today work together in large research laboratories. Their contributions, which are an important part of the story of the evolving MSE, have led to many new materials—cellophane, nylon, dacron, teflon, synthetic rubber, foam rubber, etc.—which have entered our daily lives. This experience has also shown that new materials can be designed for specific applications almost as easily as machines can be designed on the basis of the principles of mechanics and mechanisms.
Crystallography had little relationship to practical materials until well into the present century. Its lively development from roots in the 17th century depended partly on its utility in the classification of minerals and partly on the attractive elegance of the mathematical formulation of the external shapes of crystals and later in the theory of crystal lattices and symmetry groups. Despite brilliant early insights, notably by Robert Hooke, into the relation between crystal form of chemical constitution, the concepts were not formalized until the very end of the 19th century. The application of even this knowledge to practical materials was delayed by the curiously-slow recognition that it is internal structure rather than external form that makes a crystal, and that virtually all solid inorganic matter is composed of irregular nonpolyhedral crystal grains packed together. A most important step was Sorby’s establishment of methods for the microscopic study of rocks. Then, in 1863, he revealed the microcrystalline structure of iron and steel in which he identified seven constituents of different chemical and structural nature which were responsible for the well-known differences between various forms of ferrous materials.
Twenty-five years later, this began to interact with new chemical knowledge and especially with the growing body of chemical thermodynamics to permit observation and understanding of structural differences on a larger scale than that at which physicists and chemists had been working previously. Then, rather suddenly, the discovery of x-ray diffraction provided a tool for studying basic interatomic symmetries, and eventually all structural levels were conceptually connected. This discovery by von Laue and his associates in 1912 and particularly the prompt development of the use of x-rays in the study of the crystalline state by the Braggs in England completely altered the attitudes of pure scientists toward materials, and gave a framework within which all types of solids can be understood. It did to
physics what the polymer molecule had done to chemistry.60
THE NEW SCIENCE OF MATERIALS AND ITS RELATION TO PHYSICS
The modern technologies of aerospace, nuclear engineering, semiconductors, and the like, coincided with the development of theoretical and experimental studies of materials which underlay the new and more sophisticated demand. As we have indicated, the new materials concepts had been developing throughout the 19th century and the first half of the 20th century. For example, the growing involvement of physicists in structure-sensitive properties synergized solid-state physics and metallurgy. As Cyril Smith has pointed out, “Theories of deformation, of the nature of inter-crystalline boundaries, of transformation mechanisms, and many other subjects popular today were advanced and discussed by metallurgists decades before physicists discovered that there was any interest in this scale of matter. But x-ray diffraction inevitably led the physicist into contact with a whole range of solids, and made imperfections unavoidably visible. By 1930 there had been postulated several different types of imperfection—and those resulting from gross polycrystalline heterogeneity and various types of mechanical and chemical imperfections within an ostensibly homogeneous single crystal. These models provided satisfactory explanations of many age-old phenomena. An extremely fertile period of interaction between metallurgists and physicists resulted, now, fortunately extending to those who work with ceramics and organic materials as well.” 61
Perhaps the major conceptual change was the new way in which physicists began to look at matter. If they thought of the structure of matter at all, 19th-century physicists did so in terms of Daltonian atoms and molecules, finding therein the foundation of the superb kinetic theory of gases and all of the stereological variability they needed. The great physicist von Laue remarked that, in the 19th century, physics had no need of the space lattice. His own discovery of x-ray diffraction in 1912 changed all this. It provided an admirable experimental tool for studying atomic positions in crystals and it interacted fruitfully with the new quantum theory of solids. Only the opening up of a route to the even more exciting structure within the nucleus of the atom prevented this from becoming the main concern of physicists. As it happened, it was not until the late 1940’s that the new branch of physics, that of the solid state, began to take form and flourish. In the next decade, it came to be numerically the most important of the subdisciplines into which physics was dividing.
The development of many specialized branches of physics had resulted in some loss of the physicists universality that the proudly claimed early in this century. He cannot possibly be equally in touch with solid-state physics, biophysics, optics, nuclear physics, fluid dynamics, chemical physics, plasma physics, particle physics, high-polymer physics, and physics education, to
list simply the divisions of the American Physical Society and the associated societies within the American Institute of Physics, Yet, these specialized physicists all proudly claim their allegiance to physics, and their professional interests are coherently maintained. In the case of the field of MSE, there is even more diversity than in physics, and the sense of coherence is at present only rudimentary. Professional concern for all its branches is not instilled in university training, and it is not an essential consideration for maintaining status in the profession. Neither a metallurgist nor a polymer chemist nor a solid-state physicist working in the field of MSE tends to think of himself primarily as a materials scientist or engineer. Why is this? The intellectual, the technical, and the social needs all seem to favor the formation of a clearly-defined profession uniting the disciplines and providing an opportunity for a life’s work in the area made particularly rewarding by interactions with others in the whole field.
The difference between the two forms of association represented by physics and MSE appears to lie in history. The diversification of physics occurred by the gradual condensation of the subdisciplines, at first with no sharp boundary, within a pre-existing framework that encompassed them all. Conversely, all of the component parts of MSE, whether scientific, technological, or industrial had existed for centuries without much connection; the new unity has occurred by the joining of previously-defined entities rather than in the division of a larger entity into smaller parts. At the present stage of maturity, physics and MSE do not differ much in the structure and relationship of their parts, but the origin of the subdisciplinary divisions between the interfaces and the mechanism of their growth were vastly different. A highly specialized physicist classes himself with other physicists because at an earlier stage physics did include both fields embryonically. Solid-state physicists, polymer chemists, thermodynamicists, and designers or processers of materials have not yet had sufficient time to develop emotional attachment to the new realignment which is coming into being as a result of both social and intellectual factors. By its very nature, the formation of a new superstructure is harder to bring about than the progressive differentiation of a unified field into subunits because it entails greater changes of the units The present report, by illustrating both the difficulties and the potentialities of the new grouping will, it is hoped, encourage the formation of trial institutions from which might come the pattern of the future.
The properties of the materials that we fabricate and use derive only indirectly from the properties of the simpler systems that lend themselves to rigorous treatment by the physicist. The engineering properties mainly characterize large aggregates of atoms and stem from the behavior of electrons and protons within a framework of nuclei arranged in a complex hierarchy of many states of aggregation. By way of analogy, one cannot visualize the Parthenon simply by describing the characteristics of the individual blocks of pentellic marble that went into its construction, still less by analyzing the grain and crystal structure of the marble itself. The Parthenon would not exist without all these but it is more than an aggregate of crystals, more than a collection of marbles; it is a structural masterpiece reflecting
even embodying, the spiritual, economic, and technological values of a great civilization. To understand a material it is necessary to know the numbers of different kinds of atoms involved, but it is the way these are put together which basically characterizes the material and accounts for the properties that an engineer uses. The main feature of the new approach to the science of materials is recognition of the importance of structural interrelationship, just as on an engineering level it is an awareness of the interrelationship between a given component or device and the larger system in which it is operating; correspondingly on the social level, each family’s needs and deeds must fit in with others to make a world of nations.
The new approach to the science of materials is based on the recognition of the full complexity of structure and the fact that the properties depend on it. Once this principle was grasped, materials scientists and engineers could apply it to all kinds of materials and find the underlying unity behind the many classes of materials that had in previous times been studied, produced, and used in totally separate environments.
Materials science is limited, of course, by the laws of nature but there are enough laws and enough atoms of different kinds to produce an almost endless diversity for the materials engineer. There are many new complex structures to be discovered and exploited. Materials engineering is more analogous to the geographic discovery of new continents and cultures than it is to the discovery of the principles of gravitation, navigation, or meteorology. To be sure, materials engineers have to work within the laws of nature, but they are also at home in areas too complex for exact fundamental theory and have learned to combine basic science and empiricism.
Although this new approach to materials took form first in the field of metallurgy, the principles have meaning for all materials—ceramics, cement, semiconductors, and both biological and synthetic organic polymers. It is beginning to influence geology, as in the past geology has influenced it. Composite materials with structures combining two or more of the basic types of materials on a scale greater than the atomic have, perhaps, the greatest future of all. The dominance of crystalline materials is already being challenged.
MSE is as useful to those concerned with production as it is to those who wish simply to understand. On one hand, studies of solidification, deformation, and phase changes apply to the processing of all kinds of material, and on the other, methods of fabrication that have been successfully developed for one material can solve production problems for another. The influence of ceramics on powder metallurgy is a classic example, but note the transfer of metal-shaping and joining techniques to the new polymers and the application of metallurgical thermodynamics, primarily stimulated by the requirements of the steel industry, to the production of other metals.
When science began to be applied to materials technology, it was done so first at the production end, for only here was it economically feasible. The complexity of structure-sensitive properties which were of concern to the user prevented the application of helpful science until quite late. The early materials were general purpose ones and the consumer, whether an artist or an engineer, selected what he wanted from a small catalogue. Science at first controlled the chemistry of production, the efficiency and reliability of smelting. Not until well into the 20th century did the structure-property
concept take hold, but when it did a common basis was provided not only for iron and nonferrous metals, but also for ceramics and, more recently, organic materials within the same body of knowledge. Science not only offered an explanation for the many aspects of properties that had been discovered empirically, but it pointed the route to improvement and even totally new materials designed with specific properties in mind.
The end-use and the preparation of materials have now been joined in MSE. No longer is the primary producer’s profit dominant, but profit comes from the best analysis of needs and possibilities. The 19th-century engineer selected the best material that was available and improved it marginally. The 20th-century engineer can state what he wants and has far more options. Although in both cases economics dictate, it is now at least as much end-use economics as production economics.
Another relevant factor is the closer junction between science and engineering at all levels. Specialization is needed now more than ever before, but it must be in resonant communication. A new level of organization seems to be emerging, with specializations deepening, but with enhanced communication between them. Diversity is an essential characteristic of MSE, but there now exists a means of communication. The science of materials, their engineering design, and production engineering at both the chemical and mechanical stages are all interrelated; none is in isolation for each affects the other. A new kind of man is necessary to encourage the liaison, a kind of intellectual manager who, knowing something of many fields, makes his contribution by promoting balance among the disciplines and foreseeing areas likely to become limiting. As it happens, each material has its own complex of requirements, for even when using the same basic shaping techniques, the temperature and forces involved and the sensitivity to atmospheric and other contamination are different. Moreover, the availability of special properties means special uses, and the more specialized the material the more the materials engineer must know the effect of all production variables on successful application. One man cannot possibly encompass all aspects with equal detail, but the validity of MSE lies in the recognition that a certain commonality of problems exists.
The new structure-property viewpoint has served to bind together and to enrich the many strands of pure science which interact in the field of MSE. Without this contact, the crystallographer would focus mainly on ideal crystals; with it, he has been made aware of not only the difference between monocrystalline and polycrystalline matter, but also with the whole range of crystalline imperfections. For the first time in history scientists have been able to contribute to the understanding of structure-sensitive phenomena. Even in 1920, for example, textbooks on the properties of matter completely ignored most useful properties of interest to the metallurgist, and the strength of materials, as taught to the practical engineer, was essentially a simplified form of elasticity theory, once an important part of mathematical physics.
ENGINEERING ATTITUDES TOWARD MATERIALS IN THE 19TH CENTURY
It should be noted that studies of the strength of materials during the early part of the 19th century were centered in France, where the Ecole Polytechnique, the famous French engineering school, had been founded in the last decade of the 18th century and where theoretical investigations of both technical and scientific phenomenon reached a high mark. Governmental policy fostered not only the foundation of this school by also encouraged its graduates to use a scientific approach to practical problems. In the Department des Ponts et Chaussees and related enterprises, the best theory and the best empirical tests were merged, and contact with practical problems inspired some advanced pure mathematics at the hands of Navier, Poncelet, and others.62
For most of the 19th century, England’s contribution to the study of the strength of materials consisted mainly of empirical investigations of the strength of various building materials. William Fairbairn (1789–1874) and Eaton Hodgkinson (1789–1861) carried out tests on beams and other shapes of wrought iron and cast iron, and iron-framed buildings became common. In Germany, engineering schools based upon the French model were founded, but a more practical bent was given to the education and their students mainly took positions in private industry.
The growth of the railroads led to many, primarily empirical studies of the strength of materials. Fatigue in metals was first studied in connection with railroad and bridge components. An example of the empirical approach employed by British engineers is the fatigue-testing machine (consisting of a rotating eccentric which deflected a bar and then released it suddently), Captain Henry James and Captain Galton concluded that iron bars will break under repeated loads only one-third of which was needed to break them on a single application.
Several advanced industrial nations had set up material-testing programs or laboratories, and an International Congress for Testing Materials was established. In the United States such official testing had begun with the examination of iron for boilers in 183063 and was extended in the 1850’s with emphasis on materials for cannon. A Board for Testing Iron, Steel and Other Metals was appointed by the President in 1878. Its report issued ten years later includes innumerable original tests and a comprehensive study of the state of knowledge on materials, mostly metallic.64 The aim was limited to the determination of the pertinent properties of materials that were available, carefully characterized by chemical analysis and by a description of the method of manufacture. Nevertheless, these programs and the carefully-
written specifications under which materials were to be purchased forced an intimate contact between government, manufacturer, engineer, and scientist of a type foreshadowing MSE. The properties measured were initially almost entirely the mechanical properties of concern to the engineer and the materials producer, simply aimed to balance these against the requirements of fabrication. In the 1890’s, metallurgists were beginning to study microstructure in relation to mechanical properties, and other properties were becoming important, especially in connection with the electrical engineering industry. Another kind of man investigated electrical and magnetic properties of materials for their scientific interest.
In the first two decades of the 20th century, theoretical physicists began to understand the interior of the atom, and developed quantum mechanics which gave a marvelous key to the differences between classes of solids. This interacted nicely with the findings of the new x-ray diffraction techniques, and real materials became a concern of the physicist for the first time. Not, however, until after World War II did solid-state physics become a well-recognized part of either physics or materials science. Then, in addition to ideas and sophisticated instrumentation for structural studies, physicists contributed techniques for measuring properties of materials—magnetic, electrical, thermal, and optical properties—whose studies had been previously largely a matter of guesswork.
In the 1920’s, metallurgy was already beginning to move from its age-old chemical orientation to consider the properties of materials in terms of both composition and microstructure. Increasingly, the metallurgist found stimulation by working on topics that impinged on physics, to the advantage of both fields.
This changing emphasis did not mean that metallurgy became absorbed into physics any more than it had been absorbed into chemistry at an earlier date; instead, the metallurgist had uncovered phenomena which, in a sense, defined problems for both the chemist and the physicist. Nor did the newly-forged links with physicists require the metallurgist to lose contact with chemists; rather, the chemical component of MSE will be enriched in the future by the links with the organic traditions of the polymer chemist and the biochemist. By the end of the 1950’s, materials science had been transformed into an multidisciplinary activity, utilizing tools, concepts, and theories from many different branches of science.
The growth of the scientific technology in the study of materials during the 19th century parallels a similar development in other fields of engineering.
The classic examples usually cited in studies of science-technology relationships in the 19th century are thermodynamics and electricity. In the former case, technology presented problems for science; in the latter, science presented potentialities for technology. The materials field incorporated both. Technology was also drawing closer to science in another way: one of the most important was the notion of the development of engineering “laws” based on precision, quantification, and mathematization in the form of semi-empirical equations. “Engineering science,” differing from “pure science” in its motivation was carried out by men who occupied positons intermediate
between the pure scientist and the practical engineer.65 In both instances, objectives were limited to permit the formulation of mathematical relationships, but those of science were self-chosen to be soluble while those of engineering were set by the importance of the need. The engineer could not be satisfied just with understanding something in principle; it had to work, but he could use in his equations many empirically-measured coefficients, even of obscure origin. Furthermore, there were many natural phenomena not investigated by scientists but still meaningful to technologists, and so it was necessary for the technologists to conduct their own scientific investigations in some areas in more detail and on more materials than might be needed for the validation of scientific principles.
As technology has become more scientific and mathematical, and as scientists and engineers tend to work together on many problems, the old distinctions between them are disappearing because each absorbs part of the other’s viewpoint. In many cases, we must look into the context in which the work is done in order to decide whether it is scientific or technological. For example, the engineer often discovers gaps in basic scientific knowledge which must be filled before his technological task can be completed. The engineer fills the gap by doing what in another context would be called fundamental research, but because he needs it, it is called applied research.66
On the other hand, scientists often do engineering in the development of their instruments—as in the building of telescopes, in the improvement of high vacuum techniques, and the production of high voltages in particle accelerators—and pure science is often conducted by those with practical aims, for example, the basic studies of recrystallization which came out of work on tungsten lamp filaments and the semiconductor research inspired by wartime radar needs. Early in the 19th century, Faraday’s work on optical glass was classic (though not industrially fruitful), and E.Schott’s research on new glass compositions in the late 1800’s was a model MSE of scientific and industrial coupling which gave Japan a virtual monopoly on optical glass until World War I forced other countries to copy the pattern.67
The purposes, the methods, and the goals of scientists and technologists remain different, but the two kinds of practitioners have become more understanding of each other’s roles and capabilities. Nowhere is this more true than in the field of MSE.
THE TECHNOLOGICAL REVOLUTION OF THE TWENTIETH CENTURY
Twentieth-century technology has been characterized by major changes in approach, method, and organization. The change in approach is manifested by the merging of science and technology, as indicated above. Change in method includes the introduction of purposeful and systematic attempts to innovate in order to meet specified needs and wants. The change in organization is reflected in the phrase “Research and Development” (R & D), which involves the employment of teams of people representing different disciplines—a phenomenon unique to recent times.68
These characteristics of the technological revolution of our times are to be found in different fields. For example, recent advances in agriculture at least match those in MSE, and are characterized by some of the same elements: the application of scientific study to the basic biology (plant genetics and the mechanism of growth), to the chemistry of insecticides and fertilizers, and to the technology of irrigation as well as the harvesting and preservation of agricultural products. Most important was the interaction of all these with each other—and with the economic and practical environment.69
This technological transformation in the 20th century seems to have been primarily dependent upon the organization of brainpower, that is, knowledge. There are many nations in the world today which remain underdeveloped despite their possessions of vast natural-materials resources, while some materials-poor nations are among the most prosperous. Partly, this is because the latter have undergone industrialization and hence have built-up industrial strength in the past, which continues its momentum; but largely it is because they possess know-how, the knowledge which enables them to organize their technology to overcome deficiencies in energy or materials. This state-of-mind is stimulated by productive partnerships between people of quite different motives, representing a great variety of disciplines, and associated with many different institutions. This is especially so in MSE.
The union of science and technology characteristic of American technical advance in so many fields has had some spectacular successes in MSE. Indeed, MSE was central to one of the greatest “breakthroughs” of the past quarter century, the development of semiconductors. Previous technology contributed little to this innovation; the first observations came from empirical studies by physicists of the electrical behavior of all available materials in the 19th century. The first commercial utilization of semiconductors (excluding carbon) was the Nernst lamp of 1901—then followed copper-oxide rectifiers, silicon-crystal radio receivers, and eventually radar, which was associated with some theoretical progress during World War II. The major advances in both theory and practice were made in 1947–49 in an industrial laboratory—the Bell Telephone Laboratory—where the transistor was developed by a combination of theoretical and experimental scientists and technologists, doing
everything from the development of special materials through device technology to the most fundamental physics of matter and circuitry.70
The recent growth of MSE can, in no small measure, be attributed to the increased recognition by industry of the value of physics: this new attitude toward materials has merged well with the qualitative structural approach that had ripened quite independently within the metallurgical profession. The interaction worked both ways: whereas it might be said that the physicists took the lead in semiconductor research, the quantum theory of alloys began as alloying rules developed somewhat empirically by an academic metallurgist, Hume-Rothery, before it became respectable physics.71
Similarly, chemical thermodynamics inspired extensive investigations of equilibrium diagrams based on thermal and microscopic analysis of alloys. Metallurgists soon found many metastable structures about which thermodynamics had said nothing, and, interacting with engineers, they used the microscope to study the effect of deformation on microstructure. Only much later did such phenomena become part of the purer science, or influence work on other materials such as polymers and ceramics.
One hears much these days about the trend toward increased specialization in all fields. This is certainly true of the component parts of MSE; and yet the field as a whole ha a characteristic which runs counter to this. For although there are many disciplines involved in MSE, it is in their multidisciplinary cohesion that the value lies. MSE by its very nature encourages communication among practitioners of different disciplines; it also encourages people to learn more about auxiliary disciplines; and, most importantly, it demands interaction among basic research, applications, and means of production. It is this systems approach which helps distinguish MSE from its individual predecessor disciplines. Although disciplines are still needed, there must be cross-fertilization among disciplines in MSE, and its practitioners must bear the whole in mind while peering more deeply into their separate parts. The common structural principles underlying the properties of various classes of materials make this possible—and, in fact, underlie the fruitful contributions which the different disciplines can make to the understanding and development of materials.
The new approach entails viewing a host of formerly unrelated activities and processes as parts of a larger, integrated whole. It permits today’s scientists and technologists to speak of “materials” as well as of steel, glass, paper, or concrete. True, each of these has its own—and very old—technology. But the generic concept of materials represents different arrangements of the same fundamental building blocks of nature. The “materials revolution” allows us to decide first what end-use we want and then select or fashion the material to fulfill that need.72
An important aspect of 20th-century technology is a change in the organizational form in which innovation appears, and this is particularly the case in MSE. The old idea of separate or individual inventors working in isolated fashion on problems of their own selection has been largely replaced by R & D groups working toward a defined objective in an industrial research laboratory, a university laboratory, or a government laboratory, all of them bringing together specialists in different scientific and engineering specialties. This kind of application of science to technology was already visible in the 19th century in the optical-glass industry, in the German dye and pharmaceutical industry, in the development of the telegraph and cable, and in the embryonic electrical industry; but its systematic application on a large scale is a product of the 20th century.73
The American experience in industrial R & D shows the influence of the competitive forces characteristic of a capitalist economy. At the same time, this industrial utilization of science fostered a degree of cooperation, first between business units themselves and then among various types of business, governmental, and private organizations, that expanded and deepened over the course of time.
Included among the institutions carrying on R & D was the university laboratory; it became involved in a variety of external relationships through the consultative activities of its staff members, and later through governmental sponsorship of R & D. A substantial part of the latter support was through the medium of interdisciplinary laboratories (IDL’s), which became an important vehicle for governmental sponsorship of materials research in the universities.
If, in this historic section, we have overemphasized metals, it is mainly because the history of metals has been more thoroughly explored than that of other materials. This, in turn, is partly a consequence of the fact that it was around metallurgy that the modern science of materials began to appear. There has been no history of building materials, for example, which attempts to explore both the science and the practice. Ceramic materials, with their spread from utilitarian objects to the greatest works of art, both inspired and benefited from science in the 17th and 18th centuries more than did metallurgy, but the many good histories of ceramics ignore science in favor of technology, and even the technology attracts only an infinitesimal fraction of the attention paid to ceramics as art forms. Writings on the history of organic polymers tend to be superficial, except for a few articles written with special emphasis on the work of one man or company. Moreover, there are few histories of the pure sciences themselves which give adequate attention to the continuous flow of practical problems that have come from men working with materials in novel situations. The level of complexity arising from materials interacting with everything that human beings have done and much of what they have thought for more than ten millennia precludes the presentation of a picture that is both accurate and simple, just as the complexity of materials themselves precludes description by a few simple equations.
RECOGNITION OF MATERIALS SCIENCE AND ENGINEERING AS A COHERENT FIELD
The aim and very purpose of all technology is to respond to human needs as defined in some way by society, though, of course, technology also interacts with society to stimulate new expectations and to offer new possibilities for development.
Throughout history, military requirements—either during times of war or in preparation for war—have helped focus and intensify the pressures for materials development. It was quite obvious in World War II that: (a) modern industrialized warfare with its insatiable demand for some materials created critical shortages, and hence stimulated research for substitute materials and improved processing techniques, and (b) sophisticated weaponry required materials with specialized characteristics which an older and more conventional technology could not provide.
In the U.S., particularly critical were those materials that had to be imported; rubber, mica, quartz, and many of the alloying elements for steels. Research on substitutes—particularly synthetic rubber and the National Emergency steels—provided a dramatic example of the utility of the new science. Furthermore, the acceleration of innovations in jet aircraft, rockets, and nuclear energy brought to the fore critical limitations regarding the performance of materials at high temperatures. And the needs of communications, radar, and the proximity fuse made everyone aware of semiconductors and precipitated intense activity in the immediate post-war period. The critical needs for materials during World War II thus forced engineers to recognize the importance and broad potentialities of substitutes and caused a heightened sensitivity to the possibilities of developing entirely new materials of radically different properties. At the same time—and perhaps more importantly—the War inspired close cooperation between pure scientists and engineers of many different disciplines, suggesting patterns of effective interdisciplinary research that persisted into peacetime. Only about one out of ten companies using metals in a 1940 survey had a materials department; over half had such departments by the 1960’s.74
Within a few years after World War II, when the U.S. had entered into the Korean War, a national committee—the Paley Commission—was appointed to study the adequacy of materials supply. At that time, the question seemed to center on shortages of already-existing materials rather than the development of new ones. Such shortages were real. As the 1950’s began, the U.S. was simultaneously involved in the Korean War, was assisting in the restoration of Europe’s industry through the Marshall Plan, was aiding underdeveloped countries, and was still meeting the huge pent-up consumer demand following World War II, often with capital plant which had outlived its usefulness and needed to be replaced. Moreover, the concept of national preparedness during the Cold War made it seem essential to stockpile strategic materials and to build up sufficient industrial capacity for future emergencies.
The strategic requirements as America entered the Cold War era caused the Department of Defense to sponsor many investigations into materials with potential for high-temperature service, especially the entire family of refractory metals, but including many nonmetallic and composite materials. The problems were scientific as well as technological; at high temperatures, problems of oxidation, diffusion, phase change, and loss of strength often became paramount. Brittle fracture, stress-corrosion cracking, and other means of disastrous failure also attracted theoretical studies. From investigations of clad and composite materials came a new appreciation of heterogeneity on the scale that had been largely ignored since the days when the duplex steel of Damascus inspired so much research in Europe.
The advent of Sputnik posed still new challenges for the growing field of MSE. There was sudden need for the development of new materials possessing esoteric qualities for special applications in space. Furthermore, the usual engineering parameters of economy were of secondary consequence, provided the rigid performance requirements of the outer-space environment could be met. The space program also meant that governmental support for advanced new materials came from a civilian agency, NASA, in addition to AEC and the Department of Defense.
Other sophisticated materials requirements also made themselves felt. The decision to build a supersonic transport gave added urgency to titanium technology, a field that had been heavily supported by the Department of Defense since the late 1950’s. Although public opposition has relegated the development of an American supersonic transport to near-limbo, titanium remains a strong, corrosion-resistant, high-temperature structural material for other uses; much of what has been learned about the basic characteristics of this metal, its alloys and treatment, including rolling, forging, machining, and joining, will remain permanently valuable. Likewise, the requirements for turbine blades to withstand operating temperatures several hundred degrees higher than those in existing aircraft engines also prompted much materials research, and stretched the very limits of knowledge.
Similarly, as the forefront of nuclear-energy application moved from weapon to power, the material limitations broadened. In addition to the need for conventional materials of usual stability, reactors demanded dramatically unusual combinations of properties. Not only were high- or low-neutron absorption at various energies required (a nuclear property completely beyond the concern of the earlier materials professional), but the materials had also to resist radiation damage and corrosive environments under hostile conditions. Especially challenging has been the swelling of nuclear-fuel elements and graphite during reactor operation. As long as only thermal (low-energy) neutrons were involved, it could be largely controlled by the use of ceramic (uranium oxide) fuel and by dispersion of the uranium in a ductile matrix, but the new generation of breeder reactors using fast neutrons has raised the problem all over again in far more acute form. Fortunately, radiation damage itself is a useful tool in the fundamental studies of materials, and the problem has caught the interest of many fundamental scientists to the benefit of knowledge, development, and practice.
In brief, new military demands, the requirements of space, and new demands from fields in nuclear energy, missiles, rockets, communications, and the like entailed new challenges to many fields of science and technology, and often,
indeed, they were factors that paced progress. Materials were central to all.
The most advanced technological achievements today require in their materials the presence of some property to an extreme degree, combined with reasonable stability and formability. This is very opposite of the age-old materials which typically had to serve for many purposes interchangeably.
Since the late 1960’s a profound change in societal attitude has forced a new concern upon the technologist and the industrial establishment built upon his work. Through most of history, almost anything that the technologist could do was of some value to the society for, even if unbalanced, it helped to feed and house people, improve their health, and facilitate their communication with each other. Today, however, the increased density both of technologies and population makes obvious the necessity for some control within the broader framework of overall societally-oriented incentive. This puts new demands on all engineers. No longer can a smelter pour SO2 freely into the atmosphere. Modern plastics, effective detergents, and new ways of packaging products are all fine achievements from the immediate consumer’s viewpoint, but they raise many societal problems when the entire material cycle is taken into account. Of course, the engineer has always been accustomed to working toward the balancing of conflicting factors, but in this case, neither he nor anyone else anticipated the broader problems until they had reached considerable magnitude.
The problems that now face the materials engineer are technically soluble if properly tackled. Fuel and raw materials can be produced without destruction of the environment, and processes can be developed for the efficient collection and distribution of waste materials of all kinds. The recycling of scrap has been an important part of the metals industry from the beginning, and in developing countries is almost complete even today. The emphasis on the direct cost of primary production needs to be supplemented by a broader view. It is a question of seeing the problem as a whole, of designing a system that includes the economics of disposal or recycling as well as the efficient production of a serviceable part.
GOVERNMENT SUPPORT OF MATERIALS RESEARCH
The new approach to the understanding of the behavior of materials and application of this new understanding to the processing and use of both old and new materials had already begun in the research laboratories of many science-based industries before the federal government became involved in providing massive financial encouragement for the new field of MSE. At least one university—the University of Chicago—used private funds to establish a full-fledged interdisciplinary materials research institute long before government-financed interdisciplinary laboratories became popular. It would be a mistake, therefore, to believe that MSE was created by administrative fiat and by federal funding, as is sometimes believed by those who see only the tip of the iceberg. In fact, the concept and applications of MSE had already made vital contributions to the nation’s economy and defense even before many scientists and engineers had come to recognize their affinity with others involved in the same or similar fields.
The role of federal government was to accelerate and stimulate these
developments;75 In brief, to “institutionalize” the materials field, to accelerate the formation of this new field of study and practice—thus identifying a new “multidiscipline.” It did this, perhaps unconsciously, by supporting intensive research of a scientific and technological nature on some specific materials (for example, titanium), by sponsoring economic studies of the nation’s material needs, by supporting university research laboratories dealing with both specific and general materials problems, and finally by establishing interdisciplinary laboratories for materials research at several universities. The greatest result of the latter laboratories has been the training of scientists and engineers in an environment which, by intent, fostered an awareness of the many-sided nature of the field.
It should be pointed out that the philosophical principles and political practices underlying federal support of MSE are not unique to that field, although the instrumentalities employed by the government to develop MSE were unique. The governmental approach to MSE involved new means for making its support effective, and served as a useful model for advancing other scientific and technological fields to meet new and changing national goals.
We need not be detained here by the long history of federal support of scientific research and technical developments; that has existed ever since the foundation of our Republic.76 The triumphs of science and technology during World War II convinced the country’s policy makers that not only the military power but also economic power and social growth were dependent upon the nation’s scientific and technolgoical capabilities. Two decades later, it was recognized that the spiritual needs of the nation were also a function of its scientific and technological capabilities, and the direction of the vast enterprise became a matter of prime concern.
Politics, at first defined largely in military and aerospace terms, determined a rising level of national support for scientific and technical enterprises. It is not surprising that MSE participated in the general growth of the scientific-technological activity in this country. But there was more to it than that. Virtually all developments in the new areas of science and technology hinged to some degree on materials that were not in existence. The need for materials which would function in the frigid near-vacuum of space, as well as in the hot blasts of rocket engines, the requirement to miniaturize electronic equipment for control and communication, the need for materials stable under the heavy radiation and high temperatures of nuclear reactors, and many similar problems could not be solved with materials to be found “on the shelf” of existing suppliers.
The readiness of old industries to do new things, the appearance of many scientifically-oriented small industries, the growing awareness among scientists of the challenge lying at the peripheries of their professions, and the
increasing success of end-use-oriented development work, all interacted to suggest that a new field of materials science and engineering might be forming. Many university departments changed from “metallurgy” to “metallurgy and materials science” or “materials science and engineering,” thus indicating their changing objectives; there was an analogous shift from “mining” to “mining and metallurgy” and then to “metallurgy” in the 1920’s and 30’s. As in the latter sequence, these changes were accompanied by some inevitable loss, but the broader character of the new organizations will in time correct this. It remains to be seen whether the new MSE grouping is viable at universities. In order for this evolutionary interactive process to continue, there will have to be no slackening in the ongoing development of the specific sciences and areas of engineering knowledge that compose MSE.
In 1957, the distribution of funds for research in materials was divided about as follows: solid-state physics, 35%; metallurgy, 29%; and ceramics, 10%; with smaller amounts going to research in other related fields, such as physical chemistry, and, of course, more in the application of known materials for various military devices. Yet the decade from 1947 to 1957 was precisely the time when exciting developments in quantum theory of solids and dislocation theory, as well as electron microscopy and other research techniques, were bringing the metallurgist and physicist together for interdisciplinary studies of materials. It was also a time when interdisciplinary activity already flourishing in industrial research laboratories began to place demands upon the universities for the training of research scientists who could work in this newly-evolving environment. Concomitantly, mission-oriented governmental agencies, such as the Atomic Energy Commission and the Department of Defense, were becoming increasingly interested in new materials with exotic qualities for use in new energy sources, new weapons systems, and new propulsion schemes.
A number of studies indicated the need for the allocation of research funds along new directions. Several reports pointed toward the creation and development of an institutionalized form of support for materials science and engineering. The “Sproull Report” (named for Dr. Robert L.Sproull, a physics professor at Cornell, who was later to become head of the Advanced Research Projects Agency (ARPA) of the Department of Defense (DoD)) spoke of the need to support research in solid-state physics. Dr. C.F.Yost of the Air Force, at about the same time, proposed a center for research on the growth of crystals; and the Air Force, in an assessment conducted by a group at Woods Hole in 1957 also stressed the importance for greater research in materials. A Department of Defense/Materials Advisory Board study (nicknamed the “Dartmouth Report” because of the place where the conference was held) also advocated the allocation of more funds for materials research in 1957–58. The same recommendation was made in a report on “Perspectives in Materials Research” issued under the auspices of the Office of Naval Research and the National Academy of Sciences.77 These reports were unanimous in pointing to the growing importance of materials and hence for greater knowledge of their nature and behavior. But, it must be recalled, these pleas were being paralleled by many from other fields of science and engineering in the face of a general
levelling-off of governmental research support.
The successful orbiting of the Soviet Sputnik in October 1957 gave new incentive for the government to marshall the nation’s scientific and engineering resources in a way which had not occurred before, not even in wartime. As the nation came to the realization that its strength lay in its scientific research and engineering knowledge, as well as the educational base to produce the necessary manpower, unprecedented sums of government funds became available for the support of research and education. The field of MSE was one of the chief beneficiaries of this change in the national priorities.
Men at the highest level of government became concerned with the country’s requirements for materials. Through its Coordinating Committee on Materials Research and Development (CCMRD), the Federal Council for Science and Technology undertook in 1959 a survey of research needs in the area. This inquiry focused on university research capabilities and on expanding the number of graduate students in the sciences, which had reached a plateau during the years 1948–60. As a result of the CCMRD study, the Federal Council recommended a long-range effort to increase the magnitude of government-sponsored materials research in the universities and to effect a qualitative improvement through the development of more sophisticated research approaches in the field. In its 1960 report, the President’s Science Advisory Committee gave its support to the proposals advanced by the Federal Council for Science and Technology.
The Federal Council proposed the following: (a) the establishment of Interdisciplinary Laboratories (IDL) for materials research; (b) improvement of the equipment and facilities of the universities’ research capabilities; (c) increasing the production of Ph.D.’s in materials science; (d) enabling individual governmental agencies to carry out the objectives of this policy; and (e) stressing the importance of continuity in the funding on a long-range basis rather than the previous short-term commitments for specific research projects.78
The government agency entrusted with the chief responsibility for carrying out these recommendations was ARPA (Advanced Research Projects Agency) of the DoD, Itself organized in 1958 in direct response to the Sputnik impact of the preceding year, ARPA had as its mission the stimulation of innovation in areas of science and technology relevant to national defense. Its task was to prevent the U.S. from being surprised by any more Sputnik-type achievements and to keep America in the forefront of scientific and technological developments, including some whose nature seemed remote from the current activities of the three Armed Services. One of the first programs undertaken by ARPA was the initiation of the IDL program in materials science.79
Interest in advancing research in materials science was not confined to the DoD, of course; both NASA and the AEC which had previously provided the
major support continued their programs in materials research.
Three objectives were identified for the IDL program: (a) doubling the output of Ph.D.’s in material science; (b) expanding the capabilities of universities to conduct materials research and expanding the quantity of this research effort; and (c) promoting interdisciplinary mixing in research areas of interest common to various materials-related disciplines.
Interdisciplinary laboratories under this program were established at seventeen universities; twelve were funded by ARPA, three by NASA, and two by the AEC. This was a truly unique program, “aimed at producing a massive upgrading of both quality and quantity in a specific field of basic science of national interest.” From its inception in 1960 until the end of fiscal year 1972, ARPA had spent $157.9 million on the IDL program.
There were several significant aspects to the IDL funding program. For one thing, unlike the mission-oriented programs typical of DoD funding, its aim was to improve the academic capabilities for basic research and to expand graduate education. By providing the essential equipment—about one-fifth of ARPA funding went for buildings, laboratory equipment, and central facilities—the DoD through ARPA was laying the foundation for later applied research, sometimes mission-oriented. Furthermore, the detailed technical management of the IDL was handled locally by the university faculties; there was little centralized control from Washington. In addition, although emphasis was placed on the interdisciplinary characteristics of the field, considerable care was taken to avoid injuring the sensibilities of the individual disciplines involved or disturbing the normal departmental organizational structures of academia. Still another unusual element in the program was the provision for long-term contracts or forward funding.
The ARPA program did not provide total support of the IDL’s; it featured the concept of core support, that is, only part of the ARPA funds went for operating costs of specific research programs. But ARPA did provide rather liberal funds for building space and research facilities, and so greatly benefited the materials research being financed by grants for specific projects from other governmental agencies. Thus, ARPA funded only about two-fifths of the materials research in academia, with the remaining research support coming from other project-sponsoring agencies and the universities themselves.
The objective of the IDL program in training Ph.D.’s was quickly reached. In 1955, only some 86 Ph.D.’s were granted in the fields of metallurgy and ceramics; by 1965 and 1966, this number had increased to between 160 and 180. But metallurgy and ceramics do not comprise the entire field of MSE by any means. In the group of twelve universities with ARPA/IDL support, the number of Ph.D.’s granted in all materials-related fields went from about 100 in 1960 to between 350 and 360 in each of the years 1967–69. In other words, the IDL program succeeded in more than tripling the number of Ph.D.’s in the materials area. The corresponding effect on quality remains to be assessed, but the indications thusfar look favorable.
The universities were only a part of the total governmental effort to develop MSE. Fueled to a major degree, though not exclusively, by federal expenditures for the aerospace program and other new technologies, industrial research laboratories in metallurgy, polymers, and electronics had become thriving centers for the interdisciplinary “mix” constituting MSE, but
focussing for the most part on research needed for short-term applications.
While by 1965 the government had achieved its aim in the IDL program of producing more men with advanced materials-research training, the problem now became one of linking the research performed in the universities with industrial applications. It had to be translated into “hardware.” Of course, this was partially accomplished as the new Ph.D.’s moved into industrial research laboratories, but a closer linkage seemed desirable. In the mid-1960’s, the government began an attempt to connect university research with industrial problems and applications through the ARPA “coupling program.” The issue had been set forth in a report, “Federal Materials Research Program,” prepared in November 1965 by the Coordinating Committee on Materials Research and Development for the Federal Council for Science and Technology. In this, it was pointed out that “frequently knowledge exists in one branch of science and technology, but the application needs occur in another, and the flow of information between the two is not adequate.” The Committee, therefore, recommended “that consideration be given to the problem of insuring that the best available understanding of the behavior of materials be put to use in all phases of their processing, fabrication, and application.”
Although ARPA’s coupling program might not have originated in direct response to the CCMRD recommendation, it was directed to the same end, namely, the application of materials research via a closer relationship between university research and the materials requirements of the Department of Defense, and to stimulate a higher level of applied research activity in academia. Accordingly, ARPA initiated a series of joint contractual relationships for cooperative research in special areas of materials technology between a number of universities and industrial organizations and/or a DoD laboratory.80
In the original IDL program, the universities had been the prime contractors, but in the coupling program industrial organizations became the prime contractors, Three such programs were initiated in 1965 and a fourth late in 1966.
In the late 1960’s government support of R & D in all categories, including MSE, began to level off after almost a threefold increase during the years from 1960 to 1966 (almost $2 billion in 1960 to approximately $5.5 billion in 1966), Industrial R & D, which had doubled during the same interval ($7.7 billion in 1960 to $16 billion in 1966) also began levelling off, largely as a result of the decline in federal spending for defense and aerospace programs. This decline was partially due to public disenchantment with the war in Viet Nam, a winding-down of the space effort as the lunar landing became imminent, and the change in fiscal policies induced by a change in the federal administration. Moreover, the rising tide of student discontent with the military, even as a source of funds, made such involvement less attractive to universities. At the same time, growing scrutiny of the DoD budget by Congress made the military increasingly reluctant to sponsor projects which did not have direct connection with defense needs; indeed, “the Mansfield Amendment” made this compulsory.
DoD funding of university research in materials-related basic science was a victim of this change in policy. In 1971 ARPA began withdrawing its support from the IDL program, transferring it to the National Science Foundation (NSF). NSF, on its part, immediately began a review and evaluation of the ARPA/IDL program in order to decide on the proper level of continued support. The funds available were not sufficient to take up the slack left by the DoD withdrawal, especially under the inflationary increase in costs.
The change in the nature and level of governmental funding of research reflected, of course, a change in national goals and priorities. Military and aerospace requirements, which had been a major factor in stimulating government interest in MSE, no longer loomed so large in the popular mind as did questions of the environment, urban problems, and “the quality of life.” The “space race” against the U.S.S.R. had been won when the first Americans landed on the moon (apparently the Russians had withdrawn from this “race” even before this), and the “cold war mentality” had subsided somewhat with the U.S. gradual disengagement from the Vietnamese conflict. There was also the “thawing” of America’s relationship with both the Soviet Union and Red China during President Nixon’s visits to those countries in the Spring of 1972.
Since the underlying stimulus for the first federal spending for MSE was national in objectives and motivations, it is not surprising that changes in these objectives made necessary a re-evaluation of the accomplishments in the materials area. Even before the major outlines of the change in U.S. science policy had made themselves clear, the Committee on Science and Public Policy of the National Academy of Sciences had sensed a change in the situation and therefore commissioned an ad hoc Committee on the Survey of Materials Science and Engineering (COSMAT) to make the present study.
PERSPECTIVES ON MATERIALS SCIENCE AND ENGINEERING
The developments outlined in this chapter show increasing recognition of materials as a field of study which brings together theories, methods, and processes of many separate disciplines. Nevertheless, there is still some doubt as to whether or not MSE has emerged as a distinct professional field. Perhaps this is partly because the IDL program never completely succeeded in providing the close, collaborative interdisciplinary effort which it had envisaged. In too many cases, the disciplinary lines in academia, following compartmented departmental structures, each with its own high degree of autonomy, impeded the full realization of the interdisciplinary potentialities. Communication between physical and chemical scientists sometimes was difficult, and these difficulties were modest in comparison to the communication problem between theoretically-inclined scientists and practically-minded engineers. And even in those instances where the interdisciplinary mixing achieved a fully cooperative and collaborative solution to a problem, this did not mean that a feeling of common professionalism emerged.
At the National Colloquy on the Field of Materials held in 1969 at Pennsylvania State University, two leading members of the field of MSE deplored the fact that materials science had still not achieved professional status, that is, it had not yet become a sociological cluster of peer groups
with common concerns and standards. Both Morris Cohen and Rustum Roy recognized this fact. It was observed that materials scientists and engineers did not yet share a common sense of identity; they still thought of themselves as physicists, ceramists, metallurgists, electrical engineers, and the like, not as materials professionals. Roy suggested that the feeling of belonging to a single community of scientists and engineers engaged in the same line of work could only come through the institutionalization of MSE, perhaps through the development of materials-related sections within existing scientific and engineering professional societies and their grouping together across disciplinary boundaries.81
Yet, the question of professionalism among those engaged in work on materials may not be a crucial one. The real issue is: what has the emerging field of MSE, with its flexible coupling of disciplines, actually accomplished in the understanding, development, and application of materials?
Here the answer can neither be clear nor definitive. For one thing, the direct governmental support for MSE as a unique field is still fairly recent from the historical point-of-view; hence, the most significant results may not yet be apparent. After all, only in the past several years have the universities begun to turn out Ph.D.’s in materials at an accelerated pace, and they probably have not had time to make their mark in the scientific and engineering world. Moreover, any narration of the accomplishments of MSE is hampered by a lack of complete information. In order, therefore, to look at the successes and failures of MSE, we can refer only to a limited number of cases, some of them occurring before the field had emerged in its present form, some others—only a handful—coming when MSE was finally recognized as a new and different field. We might also be able to project the future usefulness of MSE by attempting to match current needs with the capabilities involved in the nature and methodologies of MSE work.
One of the major industrial achievements of recent times has been the transistor.82 The transistor was invented before there was any recognition of the uniqueness of MSE as a separate field of science and engineering; MSE cannot claim any credit for originating the transistor, but the transistor can claim some credit for MSE because it focussed attention upon the contributions which the interaction of its component disciplines might make to contemporary society. Interestingly enough, the transistor itself is an outcome of advances in fairly “pure” solid-state physics made by Bardeen and Brattain and Shockley, but it could not have come into useful existence without the inspired semi-empirical development of highly technical zone-refining methods to produce silicon crystals of fantastically high purity and controlled impurities. Moreover, the crystals had to be virtually perfect. Most of the subsequent developments in semiconductors were less dependent upon basic physics than they were upon advances in circuitry, in techniques for microshaping, and in the diffusion of impurity elements to change the local behavior of the semiconductor. No longer did the electrical components have to be separately made and laboriously connected. Every step in this
development needed intimate consultation among scientists and engineers—indeed, the boundary between the two disappeared. The background of all this lay in classical metallurgical studies of crystal growth, diffusion, and oxidation, but it was a new world which required chemical, crystallographic, and mechanical precision far outranking anything previously experienced.
Following the transistor, other devices using semiconductors proliferated. Though previously used in photocells and rectifiers on a small scale, the enhanced theory and sophisticated experience enabled far broader applications. New photoconductors gave birth to a vast array of electrostatic photocopying machines and to devices for seeing in the dark. There are hints that semiconducting surfaces may substitute for the conventional silver-based chemically-developed photographic film, itself in its development a marvel of interaction between physical and chemical research and purposeful industrial development.
The laser, so pregnant with possibilities in many fields, is an example of a discovery prompted by intellectual curiosity being rapidly developed by purposeful engineering, both needing and yielding physical insight at every stage.
A much earlier example was the development of hard and soft magnetic materials. The introduction of silicon iron for transformer cores in the early 1900’s had a spectacular effect in cutting power losses and in electrical distribution systems.83,84 As the domain theory of ferromagnetism was developed, even softer materials appeared for communication devices, and at the other extreme, there came magnets of strength and stability orders-of-magnitude better than the older steel or lodestone magnets.
The factor most responsible for the almost explosive change of knowledge and technical capacity in these materials-related areas is the conscious interaction among scientists and engineers. In all of these cases, there was some background of existing knowledge of the materials (sometimes acquired in the academic physics laboratory), but the large-scale applications arose from specifically-directed activity based on new theory and requiring constantly new techniques for realization. In the first half of the 20th century, the electrical industry made or inspired almost all the new materials other than steel.
A recent example of a spectacularly new use of old material is that of plastic composites in ablative nose cones, without which space vehicles could not safely re-enter the earth’s atmosphere. The first search for materials to dissipate the frictional heat was directed toward refractory metals and ceramics; the solution came unexpectedly from plastics, whose decomposition absorbed heat and left behind a continuously renewable porous, insulating, heat-radiating layer of char. Charring had previously been regarded as a thoroughly undesirable characteristic of organic polymeric materials. Now the principle is being applied to other high-temperature insulating problems, such as for piping.
New applications for a material can rarely be anticipated for they depend on nonmaterial factors. The properties of any kind of material embody the basic nature of matter, which underlies all things no less than do the laws of gravitation and relativity, but in the present stage of knowledge, real materials combine the basic principles in a way not often predictable. The transfer and development of materials found in a given setting to be appropriate for another is more common than designing them from first principles. Transfer instead of invention is even more frequent in technology than in science. For example, titanium metallurgy was developed intensively with military aircraft applications in mind (benefiting, incidentally, from the experience with zirconium which had proved so useful in nuclear reactors and which had many metallurgical similarities with titanium); as a result, titanium was ready for the supersonic transport when it was cancelled. However there is little doubt that the combination of lightness, strength (particularly at high temperatures) and corrosion resistance of titanium will find numerous applications, particularly since its ores are abundant in the earth’s crust and it will certainly become cheaper as its presently-difficult technology is mastered.
The development of composite materials provides another example of payoff in MSE, and also of some beneficial spillover from military to civilian technology, DoD subsidized much research on glass- and other fiber-reinforced plastics of high strength, low weight, and high modulus of elasticity. This began with ballistic missile cases and with structural components of aircraft in mind, and the success in the military applications stimulated the civilian economy for these materials in boats, truck cabs, trailer bodies, geodetic structures, fishing poles, pipe, battery cases, storage tanks, and the like. Such high-strength, light-weight structural materials may some day replace steel and concrete in the multitude of everyday applications.
Perhaps the developments in MSE most familiar to the civilian population are those involving plastics. After all, many of the more sophisticated materials, such as the transistor, although used in everyday devices, are buried inside a “black box.” What the public sees, feels, and becomes conscious of are the outsides of the “black boxes,” which are often made of plastic. Plastics in their many forms, stiff or flexible, transparent or opaque, filmy, fibrous, or massive have found their way into every room of the house (especially the kitchen), replacing older materials, usually giving cheaper objects, but perhaps less fragile, more flexible, and often more colorful if not more richly decorative than those that they replaced. The variability of the chemistry of the underlying polymeric molecule and the versatility of the fabricating techniques enable materials to be tailored to almost any specific needs.
Newly-developed materials enable new things to be done, but they also may do the old ones better or more cheaply. The competition gives life to old industries. Plastics substitute for leather, wood, ceramics, and metal in thousands of applications. Electrical transmission cables have always been covered with insulation of some kind; now synthetic polyethylene can not only be applied more easily than the older coatings, but its electrical properties and its resistance to aging are far superior.
It is in this area of substitutions that the next phase of MSE may be most visible, for it ties in with concern over the exhaustion of certain natural resources. Substitutions will enable us to make use of more abundant
raw materials than those which are less abundant. However, it must be pointed out that substitution cannot be applied in an unthinking manner, for both short-range and long-range considerations are involved. If more energy is used in providing a substitute or in recycling, this may entail an overall retrogression of environmental quality. The entire complex of materials resources must be considered; we must protect the materials resources of future generations as well as our own. Perhaps the chief emphasis should be to develop materials which can be recovered and re-used. The refuse of a city is a valuable, if dilute, ore body, whose exploitation is a challenge to MSE.
Another way to conserve natural resources is to adopt more efficient designs and to employ materials that are stronger, lighter, and more resistant to decay by corrosion. The interdependent nature of technologies and resources would seem to require the integration of our efforts in MSE into the broader goals of national policy.
However, the story of the development of MSE is not wholly one of successes. There have been failures as well as triumphs. Most of the failures, involving blind alleys of research which have not resulted in applications, go unreported; in the world of science and technology, as in the world of sports, the attention is focused on the “winners.” On the other hand, much can be learned from experiences that did not produce good results, and indeed, the history of metallurgy during the past two centuries contains many instances of knowledge gained by studying failures in processing and in applications. Yet, by and large, it is the successes—or potential successes—of MSE which achieve publicity and which attract the investment of large sums, both governmental and private, into further research in the field. There are inevitably hazards surrounding the introduction of new materials, especially when there is inadequate time for testing them under service conditions. Indeed, it is unlikely that promoters can fully anticipate either the difficulties or the successes. Initial enthusiasm for new materials has almost always been followed by a period of disenchantment, and this in turn by a period of slower, sound growth. This was true with Bessemer and his new steel process; aluminum, at first a miracle metal struggled for many years before it was accepted by the engineering world on the basis of slowly-gained experience; and more recently titanium failed to meet many of the promises of its proponents, before finding its proper, useful niche.
There has been one particularly-publicized “failure” of MSE. It was the inability of the Rolls-Royce Company to develop highly-promising new composite carbon-fiber materials to the stage of service reliability needed for the engines in the Lockheed Tristar which forced the Rolls-Royce Company into bankruptcy and threatened one of America’s leading aerospace manufacturers with financial ruin. The implications of this event were enormous, both internationally as well as domestically. Grave issues of public policy arose when the Lockheed Corporation asked the federal government for funds to sustain its operations; relations between the U.K. and the U.S. were embittered; and a serious blow was struck at the British economy. Some ascribed the inability of Rolls-Royce to meet its goals to managerial shortcomings; others blamed the deficiencies of materials scientists and engineers, who themselves still quarrel over whose fault it was. Others claim that too great reliance was placed upon the promise of a single materials development—albeit a
highly promising one—without the precaution of following up alternative technologies to fall back on in case of failure. Still others maintained that the scientists and engineers involved were endeavoring with inadequate service testing to make too great a leap beyond the existing state of the art.
The episode will probably continue to be a source of discussion and argument for many years. Perhaps no single explanation is correct; perhaps many contributing errors of judgment interacted to yield the final debacle. The entire episode has had a sobering effect upon over-enthusiastic proponents of MSE.
The Rolls-Royce episode reminds us that MSE is not an American monopoly, but like all science and technology, is international in scope. The British practitioners of MSE have also had their share of successes—indeed, most of the earlier steps toward both the science and the engineering of materials took place in England, and a disproportionate fraction of the leading scientists in the field are in the U.K. today. There is an international community of materials scientists and engineers, and it happens that many of the leaders in the materials field in the U.S. today are of foreign birth and education.
The international character of MSE might also be a matter of foreign-policy concern for the U.S., not only in regard to the availability of resources and strategic materials on a global scale, but also in terms of international competition and cooperation in science and technology.
The significance of science and engineering in contemporary life involves more than the competition among nations. It is basic to the quality of life within a nation for present and future generations. The increasing emphasis upon the ecological consequences of contemporary technologies provides another challenge to MSE. Through the development of substitute materials and the creation of new ones, MSE might be a means of insuring the continuation of a highly industrialized society and the extension of its benefits throughout the earth. We must produce and utilize materials in such a way that an ecological balance between social man and his physical environment can be maintained. In this, of course, all fields of science and engineering are encompassed and are dependent upon economic, social, and political changes. While it is true that science and technology have created some of our current problems, many of these are socio-political in origin and antedate the birth of our present industrial civilization. The solution of those problems cannot be resolved by a moratorium on science or by endeavoring to turn back the technological clock. We will need more science and technology leading to a better understanding of social, environmental, and resource interactions. In all this, MSE must certainly play a significant role. At least, MSE provides a powerful example for study of an multidisciplinary effort in a combined academic-governmental-industrial endeavor.
The most advanced MSE has heretofore been applied chiefly to the highly-sophisticated requirements of military, aerospace, nuclear energy, and electronics. Now it must be expanded to include civilian programs, the development of new materials, and new methods of processing the old ones. Will the cooperation of academic-governmental-industrial efforts be as capable of producing results in the civilian sector?
While, as Dr. Walter Hibbard has stated, MSE might be of relatively little assistance in solving contemporary needs in housing, which he believes are capable of solution by existing technology and by certain economic,
social, political changes, there are many areas of public concern which will require the attention of the materials community. MSE could exemplify the newly-awakened consciousness of the scientific-technical community toward social concerns, and it is in the context of this new challenge to scientists and engineers that the present report on MSE is undertaken. The national goals and priorities are changing, and MSE itself must adjust in order to meet the new opportunities which society poses for it—and for all of science and technology.
Finally, the COSMAT study is based upon a philosophical presupposition, which may be in some public disrepute today among those who manifest interest in the occult and who place emphasis on emotional and romantic means of solving human problems. COSMAT relies on the proposition that science and technology represent rational means of coping with the human condition and on the further proposition that MSE can make a great contribution, if wisely applied and utilized, to that end.
In retrospect, it can now be discerned that the various strands of MSE took form quite separately—the discovery and development of many different kinds of materials, the approaches of scientists, engineers, and entrepreneurs with quite different aims and methods, the individual specialized techniques for materials fabrication and utilization, and, by no means least, the educational, industrial, and social organization to weave together all of these strands.
Now that interrelationship of these things has been recognized, one can perceive within MSE a pattern of approach toward complex problems that may be transferable to other areas. It uses every bit of knowledge obtained by rigorous analytical thinking, but it applies this to real situations that have arisen as a result of a long and unique history. Brilliant successes in science for the last four centuries have come from the analytical approach, and the resulting expansion of knowledge has been enormous. But the mere aggregation of precise parts does not make an effective whole. The recent concern with ecology illustrates this in another domain. The advances of molecular biology have prepared the way for a new study of the nature of organisms, their evolution, their individual growth and morphology, and is beginning to revitalize the older fields of nature study as a whole. At the present stage of history, we have such extensive knowledge of the behavior of atoms in small groups that we are not likely to be in for any great surprises in that regime; on the other hand, scientists are only just beginning to be aware of the great richness of the phenomena arising from the larger aggregation of atoms, Perhaps the complex interactions in MSE are already pointing toward a richer science which may eventually, in an analogous fashion but on a higher level, even deal with interactions between the sciences and society. At least some practitioners in MSE see in the behavior of their materials on an atomic level a pattern of structures and structural changes which, on an ever-larger scale and with changing units, form overall patterns of higher and higher levels of aggregation encompassing more and more functions. One can also find in materials a suggestive metaphor that may be applicable to many other areas—a nucleus of a new event appearing before its environment is ready for such a change will not persist. In other words, anything whatever takes meaning only by interaction with things external to itself, and that will surely be true for MSE.