Molecular dynamics simulation of the grain boundary sliding behaviour for Al Σ5 (2 1 0)

In this study the grain boundary sliding (GBS) behaviour driven by a constant shear rate or shear force was investigated for the Al Σ5 (2 1 0) grain boundary at 500-750 K. It is found that regardless of the type of driving force, the bi-crystal system tended to resist the force applied by GB rotation which resulted from the surface strain, GB migration, or GB coupled motion. The GB generally rotated to the (1 0 0) plane of the left grain by 26.57° and in particular cases to the (0 1 0) plane of the right grain by 63.43°. Under a constant shear force the GBS only experienced a certain GB rotation and slid away when a threshold stress was reached. This threshold stress decreased with the increase of temperature, but under a constant shear rate, the GBS was strongly related to the temperatures. At 500 K, the GBS experienced a relatively complicated process involving GB migration, coupled motion, grain rotation, released defects and the beginning of cracks, while at 750 K, GB rotation dominated GBS behaviour.