Materials Frontier No.140
Title: Current Trends in Research on Grain Boundaries in Metals and Ceramics
Speaker: Professor Greg Rohrer, Department of Materials Science and Engineering, Carnegie Mellon University,USA
Venue: Yao Zheng Hall (formerly 500),MaterialBuildingA
Inviter: Prof Deliang ZHANG
Gregory S. Rohrer is the W.W. Mullins Professor of Materials Science and Engineering and the Head of the Materials Science and Engineering Department atCarnegieMellonUniversity. He received his bachelor's degree in Physics fromFranklinandMarshallCollegein 1984 and his Ph.D. in Materials Science and Engineering from theUniversityofPennsylvaniain 1989. He has authored more than 220 publications in the areas of defects and interfaces in crystalline materials. He has been recognized by a number of awards, including the Ross Coffin Purdy Award of the American Ceramic Society (2002), the Richard M. Fulrath Award of the American Ceramic Society (2004), and the Robert B. Sosman Award of the American Ceramic Society (2009), and the W. David Kingery Award of the American Ceramic Society (2014). Rohrer is an Associate Editor of the Journal of the American Ceramic Society, was chair of the Basic Science Division of the American Ceramic Society in 2005, and was chair of the University Materials Council in 2011.
Grain boundaries in metals and ceramics are the interconnected defective regions of the material that hold together the more perfectly crystalline parts of polycrystalline solids. Therefore, they strongly influence the mechanical integrity of the material, atomic transport through the material, and a number of closely related physical properties. The complexity of these defects has made them difficult to study in the past. However, new characterization techniques and advanced computation have recently led to significant advances in our understanding of grain boundaries and that will be the main topic of this talk. Specifically, I will review new trends in three dimensional orientation mapping experiments using the SEM and high energy X-ray diffraction. I will also review findings derived from large data sets of grain boundary populations and energies that are being developed by experiments and calculations. Finally, I will discuss structural and chemical transitions at grain boundaries that can drastically alter the interfacial properties of materials.