报告人: Dr. Xiaoxue Qin, Department of Mathematics, The Hong Kong University of Science and Technology 

时间:2020年10月23日上午 10:30-11:30 地点: 浙江大学玉泉校区欧阳纯美楼 316 

摘要:  We present three dimensional continuum models for the energy and equilibrium dislocation structure of low angle grain boundaries and for the dynamics of low angle grain boundaries incorporating the dislocation structure. The orientation-dependent continuous distributions of dislocation lines on curved grain boundaries are described conveniently using the dislocation density potential functions. In the first part, we present a continuum model to determine the dislocation structure and energy of fixed low angle grain boundaries in three dimensions. The equilibrium dislocation structure is obtained by minimizing the grain boundary energy that is associated with the constituent dislocations subject to the constraint of Frank's formula. In the second part, we develop a continuum model for the dynamics of grain boundaries in three dimensions that incorporates the motion and reaction of the constituent dislocations. The continuum model includes evolution equations for both the motion of the grain boundary and the evolution of dislocation structure on the grain boundary. The critical but computationally expensive long-range elastic interaction of dislocations is replaced by a projection formulation that maintains the constraint of the Frank's formula describing the equilibrium of the strong long-range interaction. This continuum model is able to describe the grain boundary motion and grain rotation due to both coupling and sliding effects, to which the classical motion by mean curvature model does not apply. Comparisons with atomistic simulation results show that our continuum models are able to give excellent predictions of the energy, dislocation structure, and dynamics of low angle grain boundaries. 

联系人:王何宇(wangheyu@zju.edu.cn) 

报告人介绍: 秦晓雪博士, 本科、硕士分别毕业于山东大学太阳成集团tyc411和太阳成集团tyc411(中国)有限公司-百度百科。 后在香港科技大学攻读博士学位，师从项阳教授。2019年底获博士学位后继续留校任博士后研究员。她的研究方向主要为微分方程数值解，材料力学计算，以及晶体材料的错位结构计算。在本次报告中，秦晓雪博士除了介绍自己近期的研究工作以外，还将对香港科技大学数学院今年的博士研究生招生和申请做简要的宣传。欢迎有兴趣的老师和同学参加(欢迎本科同学)。