Mechanical and Civil Engineering Seminar

Mechanical and Civil Engineering Seminar Series

Title: Grain Growth in Materials and the Role of Deformation

Abstract: Many materials are composed of small crystallites, or grains, that have lattices of different orientations. The boundaries between the grains can move to reduce the total grain boundary energy of the polycrystal. Since many mechanical and physical properties of materials are functions of the local grain morphology, grain growth can be used to design materials to yield a desired set of properties. The predictive power of models for grain growth is critically dependent on understanding the mechanisms governing grain boundary movement. The mobility of grain boundaries is thought to be determined by the crystallography of the adjacent crystals. However, using a rapid throughput experiment we find that the mobilities of grain boundaries can vary by three orders of magnitude and are largely independent of the grain boundary crystallography, implying that grain growth is not solely governed by a reduction in grain boundary energy. On reason for this lack of independence is that deformation is induced by the motion of grain boundaries. The mechanism for the resulting large stresses and the implications of this on the grain growth process will be discussed.

Bio: Peter Voorhees is the Frank C. Engelhart Professor of Materials Science and Engineering at Northwestern University, and Professor of Engineering Sciences and Applied Mathematics (by courtesy). He received his Ph.D. in Materials Engineering from Rensselaer Polytechnic Institute and was a member of the Metallurgy Division at the National Institute for Standards and Technology until joining the Department of Materials Science and Engineering at Northwestern University. He has received numerous awards and is a fellow of ASM International, the Minerals, Metals and Materials Society, and the American Physical Society. He is a member of the American Academy of Arts and Sciences. He has published over 350 papers in the area of the thermodynamics and kinetics of phase transformations

NOTE: At this time, in-person Mechanical and Civil Engineering Lectures are open to all Caltech students/staff/faculty/visitors.