Grain boundary rotations in solids.

A new physical mechanism of plastic flow in solids is suggested and theoretically described. The mechanism represents stress-driven rotations of grain boundaries (GBs) in subsurface areas of solids. The stress and energy characteristics of the GB rotations are calculated. In the case of nickel, we find that such rotations are energetically favorable processes in a wide range of GB parameters. Our theory is consistent with the experimental observation [D. Jang and J. R. Greer, Scr. Mater. 64, 77 (2011).] of GB rotations in deformed nanocrystalline nickel nanopillars.