Transformations of grain boundary dislocation pile-ups in nano- and polycrystalline materials

A theoretical model is suggested which describes several types of transformations of grain boundary dislocation pile-ups at triple junctions of grain boundaries in (super) plastically deformed nanocrystalline and polycrystalline materials. Ranges of parameters of defect configurations are revealed at which the transformations considered are energetically favourable. The role of transformations of grain boundary dislocation pile-ups at triple junctions of grain boundaries in plastic deformation processes in nanocrystalline and polycrystalline materials is discussed with special attention being paid to the influence of such transformations on competition between different deformation mechanisms in nanocrystalline materials.