The model of grain-boundary sliding stimulated by intragranular slip

Abstract

The theoretical model of grain-boundary sliding (GBS) stimulated by intragranular dislocation slip has been suggested on the basic of experiments on Zn and Cd bicrystals. Lattice dislocations of two grains dissociate in boundary during the spreading time t _s and form two families of mobile gain-boundary dislocations (GBDs) with the opposite sign. The motion of GBDs containing a non-conservative component is the main mechanism of GBS. The GBS rate is determined by the GBD density and by the rate of their annihilation or sink to the surface. The increase in GBD density forms additional elastic fields in the vicinity of boundary, which inhibits the entering of lattice dislocations into the boundary and weaken the source efficiency. The GBD density balance determined by the ratio of influx of lattice dislocations and annihilation of the GBDs is established. Thus the boundary demonstrates the behaviour of system with negative feedback. The model allows one to describe the GBS-time dependence in Cd and Zn bicrystals in the whole volume and to extend the understanding of the interaction of the above-mentioned mechanisms on deformation of the polycrystal.