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Memorial Tributes, Volume 11
His thesis advisor was the eminent metallurgist, R.F. Mehl. Hub remained at CIT as a research metallurgist until 1957, working with Mehl, G.M. Pound, and C. Wells. He then became a research scientist at Ford Scientific Laboratory (1958–1972), a professor at Michigan Technological University (1972–1979), R.F. Mehl Professor at Carnegie Mellon University (1979–1992), a scientist at the Naval Research Laboratory (1992–1996), and finally R.F. Mehl Professor Emeritus (1996–2005).
Hub was a giant in the field of phase transformation, to which he made many seminal contributions. One of his major contributions was defining and understanding the role of microstructure in phase transformations. In 1951, F.C. Frank had demonstrated the importance of ledges in the growth of crystals from vapor. Hub recognized the potential for similar effects in transformations in solids. In classic early work with K. Kinsman and M. Adams, he demonstrated that bainitic and other plate-shaped transformations proceeded by the motion of what he called “growth ledges.” Atomic-level ledges, or steps, which had dislocation content as well, relieved strains that would otherwise appear at interfaces between reactants and products. Hub called these defects structural ledges. In later work with a number of his students, he verified the nature of these defects by transmission electron microscopy and by computer simulations.
Hub engaged in a long, vigorous debate with J.W. Christian on the details of bainitic transformation. Hub’s view was that the diffusional composition change during the transformation accompanied the motion of ledges, while Jack Christian argued that the step structure (and accompanying shear) occurred first. Their views have been largely reconciled in the new millennium.
Hub also made significant contributions in alloy thermodynamics, the role of alloying elements in “hardenability” (retardation or enhancement of the rate of transformation) in steels, the mechanism of nucleation of new phases, interfacial energies, and the mechanism of massive transformation. His work had a substantial impact on the selection of materials for automobiles and Navy ships.
Hub was elected to the National Academy of Engineering in 1997, and he received many awards in recognition of his accom-