Paper Info
Title
Grain boundary triple junction dynamics: a continuum disconnection model
Abstract
The microstructure of polycrystalline materials consists of networks of grain boundaries (GBs) and triple junctions (TJs), along which three GBs meet. The evolution of such microstructures may be driven by surface tension (capillarity), applied stresses, or other means that lead to a jump in chemical potential across the GBs. Here, we develop a two-dimensional model for the concurrent evolution of the GB/TJ network based upon the microscopic mechanism of motion, the motion of line defects (disconnections) in the GB that have both dislocation and step character. The evolution involves thermally activated disconnection formation/annihilation and migration of multiple disconnections modes/types. We propose this crystallography-respecting continuum model for the disconnection mechanism of GB/TJ dynamics derived with a variational approach based on the principle of maximum energy dissipation. The resultant TJ dynamics is reduced to an optimization problem with constraints that account for local microstructure geometry, conservation of Burgers vectors, and thermal-kinetic limitations on disconnection fluxes. We present an analysis of and numerical simulations based upon our model to demonstrate the dependence of the GB and TJ mobilities and the TJ drag effect on the disconnection properties, and we compare the predictions with molecular dynamics and experimental observations.
Year
DOI
Venue
2020
10.1137/19M1277722
SIAM JOURNAL ON APPLIED MATHEMATICS
Keywords
DocType
Volume
grain boundary,triple junction,disconnection,grain growth,variational Onsager principle
Journal
80
Issue
ISSN
Citations 
3
0036-1399
0
PageRank 
References 
Authors
0.34
0
5
Name
Order
Citations
PageRank
Wei Chaozhen100.34
Zhang Luchan200.34
Han Jian300.34
David J. Srolovitz453.08
Yang Xiang5598.17