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题目: Three Dimensional Orientation Measurements for Studying Grain Boundary Texture, Energy, and Curvature  
时间: 2018年10月22日 星期一 上午9:30-11:00
地点: 材料楼218会议室
主办单位: 材料科学与工程学院
报告人: Gregory S. Rohrer
W.W. Mullins Professor and Department Head
Department of Materials Science and Engineering
Carnegie Mellon University, USA

个人简介:
Gregory S. Rohrer is a professor of Materials Science and Engineering at Carnegie Mellon University. He studies the structure and properties of interfaces in crystalline materials and how they influence the behavior of solid materials. His research topics include: (1) Complexion transitions at grain boundaries and interfaces; (2) Photochemical properties of ceramic surfaces; (3) Combinatorial substrate epitaxy; (4) Three-dimensional materials science; (5) Interface energy anisotropy and its effect on microstructure; (6) Structure-property relationships for hard materials. He is the editor of academic journals including <Acta Materialia> and <Journal of the America Ceramic Society>. He has 283 publications, with h-index of 57 and i10-index of 181.

报告摘要:
Grain boundary properties depend on five independent crystallographic parameters. Three can be associated with the lattice misorientation and two with the grain boundary plane orientation. Three-dimensional orientation mapping makes it possible to measure grain boundary relative areas (texture), grain boundary energies, and grain boundary curvatures as a function of all five grain boundary parameters. Recent improvements in instrumentation, including the Xe plasma FIB for serial sectioning and CMOS cameras for the detection of EBSD patterns have dramatically increased the rate at which measurements can be made. Here, we describe techniques for these measurements and present an over view of findings from a variety of metals and ceramics. One of the general findings is that the texture is stronger in the space of grain boundary plane orientation than it is in the space of misorientations. Furthermore, there are persistent correlations in materials that form by normal grain growth. For example, the grain boundary energy and the grain boundary population have an inverse logarithmic correlation. For most types of boundaries (those that are non-singular), the mean curvature has an inverse linear correlation to the grain boundary energy. However, singular grain boundaries such as coherent twins are characterized by low energy, low curvature, and high populations. Examples will be cited from studies of Ni, bcc Fe, fcc Fe, and SrTiO3.

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材料科学与工程学院