1999 TMS Annual Meeting: 1999 Institute of Metals Lecture and Robert F. Mehl Medalist

During the week of February 28-March 4, 1999, the 128th Annual Meeting & Exhibition of The Minerals, Metals & Materials Society (TMS) will be held in San Diego, California at the San Diego Convention Center.

The Robert F. Mehl Award recognizes an outstanding scientific leader in the materials science and application of metals program areas with an invitation to present a lecture at the annual meeting on a technical subject of particular interest to members.

Tickets for this honorary luncheon are $25.00 and should be purchased in advance using the on-line meeting registration form. Lunch begins at 12:00 noon, followed by a 40 minute tutorial lecture beginning at 12:20 pm. There will be no charge for those attending the lecture who do not wish to purchase the lunch.

"Fifty-Year Study of the Grain Boundary Relaxation"

About the Topic: The progress of the study on the mechanical relaxation across grain boundaries was reviewed emphasizing the information provided about the grain boundary structure especially at elevated temperatures. The study was started with the confirmation of the viscous behavior of grain boundaries. With the introduction of the concept of atomic diffusion, the models of periodic grain boundary structure consisting of "good" and "bad" regions were suggested. A recent progress is concerned with the demonstration in bamboo and bicrystals of the linear and nonlinear interaction between the lattice dislocations impinging on the grain boundary and the boundary core.

It was found recently by relaxation strength measurements that the grain boundary relaxation which exhibits the disorder of the grain boundary appeared perceivably only at temperatures above 0.4Tm and the corresponding molecular dynamics simulation showed that the CSL grain boundary structure was disrupted above this temperature. This indicates that the grain boundary structure has a transition temperature around 0.4Tm. Accordingly, the prevailing models should be modified taking account at the very start of the thermo-mechanical history of the specimens and the change occurred at the grain boundaries during their nucleation and evolution at elevated temperatures. Suggestions are made by which the measurement of internal friction and anelastic effects will render help in remodeling a realistic model of grain boundary structure to ensure a plausible comparison with experiments.

About Prof. Kê (Ge Tingsui): Prof. Kê studied at Tsing Hua University, China (B.S. 1937), Yenching University, China (B.S. 1940) and University of California, Berkeley, California (Ph.D 1943). He started his research work on internal friction and anelastic relaxation in metals in 1945 at the University of Chicago Institute for the Study of Metals and had some achievements on the study of grain boundary relaxation and non-linear anelastic relaxation associated with interaction between point defects and dislocations. This research topic was continued upon returning to China in 1949 and more progress was made there. He has published 240 scientific papers among which about 150 are concerning internal friction and anelastic behavior of metals and alloys. He invented the Kê type torsion pendulum, discovered the Kê grain boundary internal friction peak, proposed the Kê grain boundary model of disordered atomic groups and established the experimental foundation of non-linear anelasticity associated with the interaction of substitutional solute atoms with dislocation kinks in f.c.c. metals and the interaction of grain boundary with nearby dislocations.

Citations bestowed from NDRC (USA) for the participation of Manhattan Project and Long Range Radar Project (1945); medallist of C. Zener Prize (1989); C-MR Annual Meeting Lecture Award (1994); recipient of R. R. Hasiguti Prize (1996); awardee of Ho-Liang-Ho-Li Prize.