Sliding in a symmetrical tilt grain boundary, Σ5 (012) [100], was investigated by using modified Parrinello-Rahman molecular dynamics which dealt with a thermodynamic ensemble that was characterized by the number of atoms, temperature and shear stress. It was found that the grain boundary could slide in the direction perpendicular to the tilt axis, [02¯1], with the aid of a shear stress in that direction. The sliding was coupled to migration involving collective motion of third-layer atoms hopping into hollow sites between the first (grain boundary) and second layers. The critical stress which was necessary to move the grain boundary damped out almost exponentially as the temperature was increased. At above about 820K, random walk of grain boundary migration occurred without the assistance of stress. Only at much higher shear stresses could the grain boundary slide in the direction parallel to the tilt axis, [001]. This was suggested to be because this sliding mechanism did not involve coupling to the migration mode.

Stress-Assisted Grain Boundary Sliding and Migration at Finite Temperature - a Molecular Dynamics Study. M.Shiga, W.Shinoda: Physical Review B, 2004, 70[5], 054102 (6pp)