[SY-I5] Symposium I-5

[SY-I5] Motion of Grain Boundaries Based on Disconnections

^○Chaozhen Wei^1,2, Luchan Zhang⁵, Yang Xiang², Jian Han⁴, Spencer Thomas⁴, kongtao Chen⁴, David J. Srolovitz^3,1 (1.HKUST Jockey Club Institute for Advanced Study, Hong Kong University of Science and Technology, Hong Kong, 2.Department of Mathematics, Hong Kong University of Science and Technology, Hong Kong, 3.Materials Science and Engineering, Mechanical Engineering and Applied Mechanics, Computer and Information Science, University of Pennsylvania, United States of America, 4.Materials Science and Engineering, University of Pennsylvania, United States of America, 5.Department of Mathematics, National University of Singapore, Singapore)

We propose a novel approach to simulate the evolution of polycrystalline microstructures based upon a disconnection model for grain boundary (GB) kinetics. The model incorporates surface tension, applied stress, and jumps in chemical potential across GBs. The model also includes disconnection nucleation and mobility. Disconnections are line defects that lie solely with GB and are characterized by both a Burgers vector and a step height, as set by the GB bicrystallography. We first derive a continuum equation of motion for individual GBs and then for GB triple junctions (TJ) within a polycrystalline microstructure that rigorously accounts for conservation of disconnection Burgers vectors and step heights and couples the GBs meeting at the TJ. We then implement this model in a continuum simulation of GB dynamics without TJs, with TJs and in a polycrystalline microstructure. The resultant simulations provide clear demonstrations of the importance of including a crystallography-respecting microscopic model of microstructure evolution and the intrinsic coupling between stress, capillarity, and microstructure connectivity in microstructure evolution.