Response of the Al Σ5 〈001〉 {310} Symmetric Tilt Grain Boundary to the Shear Deformation Simulated by Molecular Dynamics

Abstract

In the present study, shear response of the Al (001) symmetrical tilting � 5 (310) grain boundary (GB) was investigated by a three dimensional bicrystal at 500∼750 K. It was found that the GB gradually rotated around the (001) tilt axis during the shear deformation due to the combination of surface strain, GB sliding and GB coupled motion. These rotated grain boundaries were � 5 asymmetrical or symmetrical tilt grain boundaries and led to the normal stressxx in the bicrystal system. It was also found that the response of the grain boundary to the shear deformation was closely related to the temperatures. At lower temperature (500∼650 K), further shear deformation was mediated by crack initiation or dislocation release which is closely related to the local stress condition and temperature etc. The lattice dislocations emitted from GB were identified as pure edge dislocations with Burgers vectors of � 110� /2. Interestingly, they have the (001) line direction and glide on the {110} planes. The reaction between grain boundary and lattice dislocations has been carefully discussed with its role in the shear deformation. At higher temperatures (above 700 K), after a short while of perfect coupling at the early stage the grain boundary quickly rotated and the two grains smoothly slid away from each other in the way of viscous grain boundary sliding under the shear deformation.