Has the Child of Metallurgy Walked Out on Its Parent?
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MATERIAL MATTERS
Has the Child of Metallurgy Walked Out on Its Parent? Robert W. Cahn The following article is a shortened version of the Turnbull Lecture delivered at the 2002 Materials Research Society Fall Meeting on December 2 in Boston. In 1958, the year most appropriately regarded as the birth year of materials science, Herbert Hollomon, one of its progenitors, remarked, “Out of metallurgy, by physics, comes materials science.” If one looks dispassionately at the evolution of materials science and engineering (MSE) in its early years, the truth of that assertion is indisputable. Nowadays, MSE can be classified in all sorts of ways. One basis is classification in terms of the type of chemical bonding— metallic, ionic, covalent, hydrogen—and in terms of the presence or absence of identifiable molecules. Another basis is in terms of broad categories of application— structural or functional. A third method is a refinement of the second—steels, creepresistant alloys, electrical conductors, superconductors, dielectrics, semiconductors. A fourth focuses on physical forms— castings, thin films, sheet, filaments, quantum dots, confined heterostructures, fiber-reinforced composites. The first form of classification is closely allied to the most venerable of all kinds of subdivisions: between metals, ceramics, semiconductors, polymers, and composites. My concern here is the question: Are metals and alloys, substances with metallic bonds, used in many physical forms, and representing a major part of the Periodic Table, to be regarded as materials, part of the modern domain of MSE? An absurd question? Unfortunately not. Consider, for a start, the names I have listed in Table I. Here, the category “materials” is apparently taken to not include metals, or at any rate, not all
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aspects of metals; so, metals must be mentioned separately. The stages in the changing balance between metals and other aspects of MSE are well summarized in the table of contents of a book by the late Michael B. Bever1 of the Massachusetts Institute of Technology (MIT), Metallurgy and Materials Science and Engineering at MIT: 1865–1988, written to commemorate the centenary of the first injection of metallurgy into a curriculum originally dominated by mining. Following an introductory chapter on “The Early Years,” we have successive chapters on “Mining Engineering and Metallurgy: 1889–1916”; “Extending the Scientific Base: 1917–1938”; World War II: 1939–1946”; “The Postwar Period: 1946–1950”; “The Flowering of Metallurgy: 1951–1962”; “Metallurgy and Materials Science: 1962–1972”; and “Materials Science and Engineering: 1972–1988.” This sequence maps in unmistakable fashion the rise, “flowering,” and relative decline of metallurgy as the lead discipline in a technologyfocused institution. It is clear enough that all these illogicalities derive from the fact that many organizations and periodicals that were once wholly focused on me
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