The migration of planar symmetrical tilt grain boundaries with various tilt axes was investigated. The driving force for the grain boundary migration was due to an external mechanical stress field. Low- and high-angle grain boundaries could move under this driving force, and the activation parameters for the stress-induced grain-boundary motion were different for low- and high-angle grain boundaries. The experiments revealed a sharp transition from low-angle grain boundary to high-angle grain boundary behavior. The transition was marked by a clear change in the activation enthalpy for the grain boundary motion, without any extended range. An overview was presented of existing experimental results and theoretical considerations of the structure of grain boundaries at the transition. The observation that the transition depended upon the rotation axis of the grain boundary and upon the grain boundary plane was particularly important, because this would influence the Brandon criterion which was often used in experiments and simulations of grain growth and recrystallization processes.

Transition between Low and High Angle Grain Boundaries. M.Winning, A.D.Rollett: Acta Materialia, 2005, 53[10], 2901-7