Dr. John W. Cahn developed the theory of spinodal decomposition in alloy materials by incorporating the strain energy term into the free energy of the alloy system. It has made it possible to predict the optimal microstructures of alloy materials and to maximize their functions. The theory has led to the establishment of a design guideline for the development of alloy materials and contributed to the progress of both materials science and materials industry.
Spinodal Decomposition. The 1967 Institute of Metals Lecture, TMS AIME 242: 166-180, 1968
A Microscopic Theory for Antiphase Boundary Motion and Its Application to Antiphase Domain Coarsening (Allen, S. M. and Cahn, J. W.). Acta Metallurgica 27: 1085-1095, 1979
A Metallic Phase with Long-Ranged Orientational Order and No Translational Symmetry (Shechtman, D. S., Blech, I., Gratias, D. and Cahn, J. W.). Physical Review Letters 53: 1951-1953, 1984
The Interactions of Composition and Stress in Crystalline Solids (Larché, F. C. and Cahn, J. W.). Acta Metallurgica 33: 331-367, 1985
The Cahn-Hilliard Equation: Motion by the Laplacian of the Mean Curvature (Novick-Cohen, A., Cahn, J. W. and Elliott, C. M.). European Journal of Applied Mathematics 7: 287-301, 1996
Among the structural and functional materials in common use today, only a few consist of a single component, while the large majority are alloy materials of two or more elements. To create alloy materials with ideal characteristics and functions, it is essential to control their composition and microstructure. Until the 1950s, researchers attempting to maximize the potential of alloy materials were forced to take a trial-and-error approach toward constituent selection and structural control, and design guides for optimizing the characteristics of alloy materials for specialized functions were eagerly sought.
The structure of an alloy material is determined by the requirement that its free energy of the alloy material must be a minimum. However, the techniques available to thermodynamics in the 1950s could deal mainly with homogeneous alloys. It was impossible to rigorously apply the free energy concept to controlling of the microstructure of heterogeneous alloys with microstructures formed by composition fluctuations.
Dr. John Werner Cahn established the theory of three-dimensional spinodal decomposition by extending the one-dimensional theory formulated by Dr. Mats Hillert and also by incorporating an elastic strain energy term into the free energy, leading to the intentional design of alloy materials with especially desirable characteristics. More specifically, Dr. Cahn became the first to demonstrate that the composition fluctuations needed to bring out the optimal properties of alloy materials may be determined by a materials structure formation theory based on the three dimensional spinodal decomposition, thereby proposing a technique to deal quantitatively with microstructures. This theory has since found application in the design and production of metals, glass, semiconductors, polymers, heat-resistant materials, and magnetic materials, which require a variety of properties and functions. Dr. Cahn’s research findings have also laid the foundations for the phase-field method, which is a structure formation simulation method, and also one of the hottest research topics of recent years.
As detailed above, Dr. Cahn made it possible to predict the optimal microstructures that would maximize the property and the functionality of alloy materials, by being the first to advocate that the formation and control of such materials’ microstructures resulting from spinodal decomposition may be determined by free energy in combination with elastic strain energy. Using this analysis and theory, materials scientists worldwide are now creating effective design guides for the development of new alloy materials. Consequently, Dr. Cahn’s work represents a significant contribution not only to the progress of materials science, but to the development of materials for modern society as a whole.
For these reasons, the Inamori Foundation is pleased to present the 2011 Kyoto Prize in Advanced Technology to Dr. John Werner Cahn.
Years ago, in mid-career, I read Thomas Kuhn’s classic, “The Structure of Scientific Revolutions” and finally understood why was happy to have left physical chemistry and become a metallurgist. Metallurgy was exciting to me because it was in a paradigm building stage. I would often suggest to students and colleagues that read Kuhn would help them find their niche. Most preferred the power and certainty of working with well-established laws. Some enjoyed careful observations without deep understanding as in the pre-paradigm sciences. An adventurous few wanted to do paradigm building.
As a child I loved asking difficult questions, and gravitated towards science, getting a Ph.D. in Physical Chemistry at age 24. Kuhn calls physical chemistry a mature science with firmly established laws. Most chemists were happy, that by relying on these laws, their work could be perfect. A few were working in fringe fields that did not have rules; their work was frowned on, but I found some of it interesting. I had been taught that solids were inert and thus of no interest to chemists, but after taking a course in the physics of solids, I thought otherwise. Metallurgy and ceramics were ancient crafts with an enormous amount of fascinating craft knowledge that presented opportunities for new science. I became intrigued with the possibility of creating a chemistry of solids and took a chance by obtaining a position in the Institute for the Study of Metals at the University of Chicago. Two years later I was fortunate to join the world-class Metallurgy and Ceramics Department of the General Electric Research Laboratory which expected independence from their researchers, and sponsored the full range of activities from very fundamental research, to bringing new ideas to applications. Even the occasional commercial problems we were asked to solve, gave us the opportunity to dig deeper, identify missing science, and provide sound solutions. I blossomed in that atmosphere, and quickly gained wide recognition. I valued independence and had it in my later employment at MIT and NIST. To my amazement, many of the paradigms we created in metallurgy are universally applicable and useful in many science and some social science fields. Some will be discussed in the lecture.