|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||Non-equilibrium Features of Grain Boundaries
||Dislocation Nucleation from Grain Boundary: A Comparison between Conventional MD and Accelerated MD
||Jun-Ping Du, Yun-Jiang Wang, Yu-Chieh Lo, Liang Wan, Shigenobu Ogata
|On-Site Speaker (Planned)
Dislocation nucleation from the grain boundaries (GBs) dominates the plastic deformation of materials in a confined volume, which may have a limited number of plastic deformation carriers. Molecular dynamics (MD) has been widely used in studying the dislocation nucleation events from GBs. However, the limitation of the short timescale (nano-seconds) is a long-standing shortcoming of the conventional MD studies of dislocation nucleation from GBs. Here, we used an accelerated MD method, the adaptive-boost MD, to overcome the timescale limitation and revealed a mechanism transition of dislocation nucleation from GB in Cu. At the conventional MD strain rate conditions (~108s-1), dislocations nucleate from ‘E’ structural unit of a GB by the displasive (collective nucleation without shuffling) mode. while at the experimental strain rate(~10-4s-1), the diffusive (atomic shuffling) process dominate the dislocation nucleation from the GB. The activation free energy and the activation volume show a strong dependence on temperature.
||Planned: Supplemental Proceedings volume