Bicrystal experiments on the high-purity metal showed that both low-angle and high-angle boundaries could be moved by an external shear stress. The activation parameters for grain-boundary migration were very different for low-angle and high-angle boundaries. The transition between the behaviours was sharp, and appeared to be independent of the tilt axis.

Migration of Grain Boundaries under the Influence of an External Shear Stress. M.Winning, G.Gottstein, L.S.Shvindlerman: Materials Science and Engineering A, 2001, 317[1-2], 17-20