Grain-Boundary Shear-Migration Coupling in Al Bicrystals. Atomistic Modeling

The energy of grain boundary shears is calculated for symmetric grain boundaries (GBs) using ab initio methods and molecular-dynamic modeling in order to elucidate mechanisms that control GB shearmigration coupling in typical symmetric GBs, such as Sigma 3 (111), Sigma 5 (012), Sigma 5 (013) and Sigma 11 (113) tilt GBs, in Al bicrystal. The energy of generalized grain-boundary stacking faults (GB-SF) is determined, and the preferred directions and the energy barrier are established for grain-boundary slippage. It is shown that the relative slippage of neighboring grains at certain directions of particle shears is accompanied by conservative migration of GB in the direction perpendicular to its plain. The modeling data are comparative to known grain-boundary shear-migration coupling mechanisms in Al.