tion of metallurgical phenomena and product properties. This ability should be as quantitative as possible, hence the need for emphasis on models to relate process variables and product properties. Product properties studied should include the conventional mechanical properties in addition to those related to modern coating and joining processes. Fabrication technology, with emphasis on the applications of robotization and computer-integrated manufacturing, also needs significant attention.
Researchers working on new metallic materials can now also focus on innovative processing techniques to produce “materials by design.” In this approach, the alloy designer can anticipate being able to engineer metals alone or in combination with ceramics, or in different chemical states, to optimize performance. Examples include the following:
Very fine grained, single-phase materials. These are achievable through advanced processing techniques, such as rapid solidification processing, permitting the attainment of structural refinement and control of metastable and equilibrium-phase transformation. Such materials can have excellent combinations of strength, ductility, and corrosion resistance.
Dispersion-strengthened and microduplex alloys. Again, advanced techniques such as mechanical alloying can create unique microstructural configurations leading, for example, to ideal multiaxial properties and microstructures that are stable at high temperatures.
Intermetallic compounds. Unique combinations of heretofore difficult-to-form compounds are now possible in polycrystalline, single-crystal, and amorphous forms by the use of novel processing techniques as well as compositional control and trace element additions. These promise to allow for higher-temperature, load-bearing applications.
Composites. Innovative combinations of metal matrix, intermetallic matrix, and ceramic matrix composites are clear examples of materials produced by design. Again, processing is the controlling parameter.
Thin films and layered structures. These are, perhaps, the ultimate examples of creating unique microstructures, literally by atom-by-atom layering.
Alloys resistant to radiation damage. Surface modification is one technique for developing such alloys. Other approaches based on ceramic or polymer matrices cannot be implemented until researchers learn how to design systems with less ductile materials and to incorporate them into structures. To accomplish this will require a multidisciplinary approach, including calculation (theory-assisted engineering) and modeling, particularly of micromechanical aspects.
Achieving the ideal microstructure for a particular materials system requires fundamental understanding of the many mechanisms of failure—brittle and ductile fracture, fatigue, creep, friction, and wear. Each is the product