ON THE SPREADING OF GRAIN-BOUNDARY DISLOCATIONS AND ITS EFFECT ON GRAIN-BOUNDARY PROPERTIES

The effect of dissociation of trapped lattice dislocations (TLDs) on the energy of grain boundaries (GBs) is calculated. Two possible effects are considered. The first is the change of energy of the GBs caused by the presence of TLDs cores. It was shown to be smaller than 5% of the grain boundary energy. The other, more important, is an increase of the energy of the strain fields connected with grain boundaries. Dissociation of TLDs causes an increase of incompatibility strains between plastically deformed grains. The energy of these strains is of the order the GB energy in equilibrium. The EGBDs strain fields provide a driving force for GB sliding and migration. In fact, EGBDs cannot leave the grain boundaries. Recovery of these dislocations can take place only by sliding and migration of grain boundaries.