A theoretical model was proposed for the description of the emission of partial dislocations by grain boundaries in nanocrystalline materials during plastic deformation. Partial dislocations were assumed to be emitted during the motion of grain-boundary disclinations. The latter were carriers of rotational plastic deformation. The ranges, of the parameters of a defect structure, were calculated for which the emission of partial dislocations by grain boundaries in nanocrystalline metals was energetically favorable. It was shown that, as the size of a grain decreased, the emission of partial dislocations by its boundary became more favorable when compared with the emission of perfect lattice dislocations.

Emission of Partial Dislocations by Grain Boundaries in Nanocrystalline Metals. M.Y.Gutkin, I.A.Ovidko, N.V.Skiba: Physics of the Solid State, 2004, 46[11], 2042-52