The atomic mechanism which was responsible for the emission of partial dislocations from grain boundaries in nanocrystalline metals was considered. It was shown that, in 12 and 20nm grain samples, grain boundaries which contained grain-boundary dislocations could emit a partial dislocation during deformation via local atomic shuffling and stress-assisted free volume migration. The free volume was often emitted or absorbed by a neighboring triple-junction. It was also suggested that the degree of delocalization surrounding the grain-boundary dislocation determined whether atomic shuffling could produce the displacements of the Burgers vector which were necessary to emit a partial dislocation. A temporal analysis of the atomic configurations during dislocation emission indicated that creation and propagation of the partial might be separate processes.

Atomic Mechanism for Dislocation Emission from Nano-Sized Grain Boundaries. H.Van Swygenhoven, P.M.Derlet, A.Hasnaoui: Physical Review B, 2002, 66[2], 024101 (8pp)