Models for grain rearrangement resulting from grain boundary sliding

Abstract

An analysis of grain boundary sliding (GBS) in polycrystalline solids is made using two-dimensional arrays of identically shaped grains. It is shown that GBS not requiring accommodation at grain boundary triple-points, acts in such a way as to produce a grain rearrangement in which the number of grains along the length of the sample changes. This is classified as Rachinger sliding. On the other hand, when the grains are deformed to accommodate GBS, the number of grains along the length of the sample does not necessarily change during deformation and we have only Lifshitz sliding. The implication of these models is that Rachinger's grain-shape change technique for measuring GBS is incorrect when GBS requires grain boundary triple-point accommodation. Also, these models are used to discuss some features of superplastic deformation and diffusional creep.