The Board of Trustees of the Gordon Research Conferences has established the Alexander M. Cruickshank lectures to honor the many years of service to the organization of the former director, Dr. A.M. Cruickshank. Typically, there is one such lectureship annually, for each of the principal subdisciplines of the Conferences, namely the Biological, Chemical, and Physical Sciences.

The A.M. Cruickshank lectures should focus on the major challenges and opportunities field of the particular Gordon Research Conference and be presented by a scientist active in research at the frontiers of the area. The A.M Cruickshank lectures should be bold and speculative, in keeping with the forefront nature of the Gordon Conferences. The presentation should explore an initiative, thrust or development which, if achieved, would either significantly advance that field of endeavor, or even lead to a new one.

William W. Mullins has been named as the Alexander M. Cruickshank Lecturer in Physical Sciences for 2000. Professor Mullins has had a distinguished career as an educator and researcher and is best known for his theoretical contributions to solid state science. Our current understanding of the mechanisms by which surfaces, grain boundaries, and interfaces form, move, and change shape is underpinned by Mullins' theoretical work. Mullins' contributions have spanned several decades and he continues to break new ground. His early papers on magnetically induced grain boundary motion¹, the theory of thermal grooving^2,3,5,6, the influence of capillarity on the morphological evolution of surfaces^{4,7,8,9,10,11,12}, and solidification theory¹³ are now regarded as classics. Based on this and other work, Mullins was elected to the National Academy of Sciences, received a Humbolt Research award, and the Von Hippel award of the Materials Research Society. This nomination, however, is motivated by Mullins' most recent contributions in the area of normal¹⁴ and abnormal grain growth¹⁵ and toward the development of procedures for reconstructing grain boundary mobilities from mesoscale structural data¹⁶. These papers have all been published since 1997 and, in the opinion of myself and a number of my colleagues, are of equal or greater importance than the older papers for which he is so well known.

Mullins' presentation has the provisional title, "Understanding and Controlling the Motion of Neutral and Charged Grain Boundaries During Normal and Abnormal Growth." In this talk, Mullins will refer to his most recent work and outline his thoughts on two questions of central importance to ceramic science. The first question is, what is the origin of abnormal grain growth and how can it be controlled? Abnormal grain growth is when one (or several) among many millions of microscopic grains in a polycrystal abruptly grows to macroscopic dimensions; while this phenomenon is widely observed and of tremendous practical importance, the controlling mechanisms have yet to be discovered. The second question is, how do charges on grain boundaries in ceramics influence boundary motion and microstructural evolution? Further, can external fields be used to control grain boundary motion? The answers to these questions will have a profound influence on ceramic science and engineering. While the properties of many polycrystalline materials depend on their microstructure and mesostructure, it is not yet possible to adequately control these structural length scales. Understanding the mechanisms that cause abnormal grain growth and developing methods to control this phenomenon will be a significant advance in our field with important scientific and practical consequences for the design of tailored materials.

1. W. W. Mullins, "Magnetically Induced Grain Boundary Motion in Bismuth," Acta Met. 4, 421 (1956).

2. W. W. Mullins, "Theory of Thermal Grooving," J. Appl. Phys. 28, 333 (1957).

3. W. W. Mullins, "The Effect of Thermal Grooving on Grain Boundary Motion," Acta Met. 6, 414 (1958).

4. W. W. Mullins, "Flattening of a Nearly Planar Solid Surface Due to Capillarity," J. Appl. Phys. 30, 77 (1959).

5. W. W. Mullins and P. G. Shewmon, "The Kinetics of Grain Boundary Grooving in Copper," Acta Met. 7, 163 (1959).

6. W. W. Mullins, "Grain Boundary Grooving by Volume Diffusion," Trans. AIME 218, 354 (1960).

7. W. W. Mullins, "Theory of Linear Facet Growth During Thermal Etching," Phil. Mag. 6, 1313 (1961).

8. R. T. King and W. W. Mullins, "Theory of the Decay of a Surface Scratch to Flatness," Acta Met. 10, 601 (1962).

9. W. W. Mullins, "Solid Surface Morphologies Governed by Capillarity," in Metal Surfaces: Structure, Energetics and Kinetics, ASM, Cleveland Ohio, p.17 (1963).

10. F. A. Nichols and W. W. Mullins, "Morphological Changes of a Surface of Revolution due to Capillarity-Induced Surface Diffusion," J. Appl. Phys. 36, 1826 (1965).

11. F. A. Nichols and W. W. Mullins, "Surface (Interface) and Volume Diffusion Contributions to Morphological Changes Driven by Capillarity," Trans. AIME 233, 1840 (1965).

12. E. E. Gruber and W. W. Mullins, "Extended Analysis of Surface Scratch Smoothing," Acta Met. 14, 397 (1966).

13. W. W. Mullins and R. F. Sekerka, "The Stability of a Planar Interface During Solidification of a Dilute Binary Alloy," J.Appl. Phys. 35, 444 (1964).

14. W. W. Mullins, "Grain Growth of Uniform Boundaries with Scaling," Acta mater. 46, 6219 (1998).

15. A. D. Rollett and W. W. Mullins, "On the Growth of Abnormal Grains," Scripta mater. 36, 975 (1997).

16. B. Adams, D. Kinderlehrer, W. W. Mullins , A. D. Rollett and S. Ta’asan, "Extracting the Relative Grain Boundary Free Energy and Mobility Functions from the Geometry of Microstructures," Scripta mater. 38, 531 (1998).