Remarks on the Evolution of Materials Science
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Introduction I am deeply pleased and moved to receive the 1995 Von Hippel Award of the Materials Research Society. I think it is appropriate to take a moment to reflect on the influence and support I have had from my teachers, co-workers, colleagues, and students. From the many names here, I would like to mention especially my thesis adviser Cyril Smith who is deceased, about whom I will say a little more shortly, and also a colleague and close friend of long standing, Bob Sekerka, who worked with me on morphological stability questions1"3 many years ago, and who is one of the reasons I am standing here tonight. On a more personal note, I would like to recognize the support of my family, and especially the steadfast support of my wife June, and also recognize her presence, as well as that of three of my sons here tonight. Let me turn to my talk on the evolution of materials science. First I will suggest some defining characteristics of materials science followed by some of the general trends in the field during the recent past. Then I will discuss a small sample of some exciting recent developments. After that I would like to turn to the specific subject of grain growth as an example of how models in materials-science fields evolve or develop. I will focus
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on the relation between the bubble model and the model based on the differential geometry of moving curves. This will make contact with some early work of mine and show how it developed from the work of Cyril Smith. Finally I will discuss some future needs and directions of materials science. Defining Characteristics of Materials Science The heart of materials science is microstructure at all levels. Microstructure means different things to different people, but the general idea is clear. One starts with the atomic structure, what atoms are present, and where they sit. Then there are point, line, and surface crystalline defects. Also on this scale is the configuration of polymer molecules as exemplified by crosslinking or protein folding. On a larger scale, one has the configuration and distribution of phases, grains, and interfaces in a material. Another characteristic of materials science is a focus on the time evolution of
microstructures. Examples are grain growth, coarsening, and phase transformations. Understanding and controlling the time development of microstructures under imposed conditions is of practical importance in devising processes for making materials and for preventing or retarding the degradation of materials in service. A third characteristic of materials science is a focus on metastable states. Almost every material that is of practical value is frozen in a metastable structure, usually with a high surface-to-volume ratio. Since these materials are not in equilibrium, their microstructure is path-dependent. Thus processes used to make these materials are an integral part of materials science, as exemplified by the time-temperature recipe for heattreating a steel, or the sequence of steps needed to make carbon nanotubes. Finally materia
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