Invited Speaker：Prof. Gregory S. Rohrer
【Title】New perspectives on grain boundary migration during grain growth
Time: 10:00 am, May 21st, 2025
Location:
Xingqing Campus, Zhongying Building, No. 01 Meeting Room A245-247
兴庆校区仲英楼 材料学院 第一会议室 (A245-A247）
Introduction：Prof. Gregory S. Rohrer received his Bachelors degree in Physics from Franklin and Marshall College, his Doctoral degree in Materials Science and Engineering from the University of Pennsylvania, and joined the faculty at Carnegie Mellon in 1990, where he is now the W.W. Mullins Professor of Materials Science and Engineering. From 2005 to 2021, he was the Head of the Department. Prof. Rohrer has authored or co-authored more than 360 publications. His technical contributions have been in the area of surfaces and grain boundaries, where he discovered mechanisms for charge separation in oxide photocatalysts, grain boundary texture within polycrystalline materials, and grain boundary energy changes associated with complexion transitions. He has also developed methods for three-dimensional microstructure analysis and grain boundary property measurement. Rohrer is a Fellow of the American Ceramic Society and a Fellow of the Materials Research Society. His research has been recognized by numerous awards, among which are the Cyril Stanley Smith Award from TMS and the Richard M. Fulrath Award, the Robert B. Sosman Award, and the W. David Kingery Award, all from the American Ceramic Society. In 2011, he served as chair of the University Materials Council, from 2016 to 2019 he was a member of the Board of Directors of the American Ceramic Society. He is currently the Coordinating Editor for the Acta Materialia family of Journals.
Abstract：Recent studies of polycrystalline Ni, SrTiO3, and Fe have shown no correlation between curvature and migration velocity, contradicting the observed migration behavior of individual grain boundaries in bicrystals. In this seminar I will discuss the influence of grain boundary energy anisotropy on the driving force and, more specifically, the anisotropy associated with the grain boundary plane inclination. Application of this driving force leads to the prediction that the area expansion of a given grain boundary is correlated to the difference in the energies of the grain boundaries that meet at a triple line. Experimental evidence, derived from the time evolution of three-dimensional polycrystalline microstructures measured by diffraction microscopy, is consistent with this prediction. Furthermore, the data show that grain boundaries migrate in such a way as to replace higher energy grain boundaries with relatively lower energy boundaries.
