Abstract
Accelerated molecular dynamics reveals a mechanism transition and strong temperature dependence of dislocation nucleation from grain boundaries (GBs) in Cu. At stress levels up to of the ideal dislocation-nucleation stress, atomic shuffling at the structural unit in a GB acts as a precursor to dislocation nucleation, and eventually a single dislocation is nucleated. At very high stress levels near the ideal dislocation-nucleation stress, a multiple dislocation is collectively nucleated. In these processes, the activation free energy and activation volume depend strongly on temperature. The strain-rate dependence of the critical nucleation stress is studied and the result shows that the mechanism transition from the shuffling-assisted dislocation-nucleation mechanism to the collective dislocation-nucleation mechanism occurs during the strain rate increasing from .
1 More- Received 24 May 2016
- Revised 6 August 2016
DOI:https://doi.org/10.1103/PhysRevB.94.104110
©2016 American Physical Society