报告题目：Topological and Atomic-scale Characterization of Grain Boundary Networks in Poly- and Nano-crystalline Materials and its Applications
　　报告人：Prof. Mo Li (Georgia Institute of Technology)
　　报告时间：2013年5月3日(星期五)上午09:30
　　报告地点：5号楼502-1会议室
　　报告摘要：
　　Microstructure in polycrystalline materials, either coarse-grained or nano-crystalline, is characterized by the complex topological structure of grain boundary networks which are composed of an array of geometric entities with different dimensions such as grain volume, grain boundary plane, triple junction line, and vertex point. Collectively, they contribute to the materials’ properties. To be able to achieve the desired properties of a polycrystalline material with optimal microstructure is at the heart of materials engineering: From the ancient Chinese Yue Wang Guo Jian sword to high temperature alloys in jet engines we witness a long history of human endeavor in making desired properties by controlling the microstructures in polycrystalline materials.
　　While some of these entities can be measured from experiment, a large number of them still remain inaccessible, that includes identification of the full range of topological properties and the structure characterization on atomic scales. In this talk, I present recent developed algorithms and numerical methods to characterize systematically these entities in grain boundary networks in polycrystalline samples, which are either from serial sectioning of real polycrystals or from digital microstructures generated using inverse Monte Carlo methods or other method such as phase field method. The rendered microstructures are represented by the topological and geometric properties such as the grain volume, grain boundary area, triple junction length, and their statistical properties. Most importantly we give the atomic coordinates and label the type of the topological entities to which each atom belongs in the polycrystalline and nanocrystalline materials. Such quantitative characterization, unavailable before, enables detailed and rigorous treatment of microstructures in a wide range of modeling applications including both atomistic simulation and continuum modeling. If time permits, I will also discuss nucleation and growth and their relations to microstructures.

　　报告人简介：
　　Professor Mo Li received his Ph.D. in applied physics in 1994 from California Institute of Technology. After a brief staying as a postdoctoral fellow at Caltech and the Argonne National Laboratory, he joined Morgan Stanley & Co. in New York. He came back to academia in 1998. From 1998 to 2001 he was an assistant professor at the Johns Hopkins University. Currently he is a professor at the Georgia Institute of Technology and a Thousand-Talent Program professor in the School of Materials Science and Engineering at Tsinghua University. Professor Li's research focuses on understanding fundamental properties and processes of materials, and predicting material behaviors. The approaches used in his research are a blend of those from statistical physics, solid state physics, materials science, metallurgy, mechanics and large scale, high performance computing. His research focuses on algorithm development, simulation, and theoretical analysis.

　　邀请单位：北京理工大学材料学院