Conditions of Strain-Induced Facet Formation during Interaction between a Lattice Dislocation Pile-Up and a Grain Boundary

A model describing the formation of a strain-induced facet at a high-angle boundary during its interaction with a dislocation pile-up is proposed in this work. The model of continuous dislocation distribution in a pile-up has been used to analyze the conditions under which a facet appears and to calculate its length as a function of the total Burgers vector of the dislocation pile-up and the boundary misorientation angle. The formation of a facet at a grain boundary is possible only if the total Burgers vector exceeds a certain critical value that depends on the external stress and boundary misorientation. The facet length as a function of the initial distance between a dislocation source and a grain boundary at various external stresses and misorientation angles has been calculated in the case of a pile-up replenished by a dislocation source. It is found that the material grain structure refinement and a shift of grain boundaries misorientation spectra into the region of large angles suppress strain induced grain boundary faceting. The facet formation has been shown to be accompanied by the formation of a shear band in the body of the adjacent grain.