Recent theoretical and simulation studies indicated that grain boundary motion was coupled to the translation and rotation of the adjacent grains. However, the geometry of the system could strongly modify this coupling. The evolution of grains in two geometries that were similar to studied experimental systems were simulated. The first, a small circular grain embedded in a matrix consisting of two other grains, showed that rotation could be suppressed by geometric frustration, but the coupling slows the grain boundary motion. The second, a bicrystal cut into a wedge shape, showed that free boundaries could act as sinks for grain boundary dislocations thereby stopping or even reversing the rotation caused by grain boundary motion. These results showed that an experimentally relevant theory of grain boundary motion needs to consider the effects of microstructure and sample geometry.

The Influence of Geometry on Grain Boundary Motion and Rotation. N.Bernstein: Acta Materialia, 2008, 56[5], 1106-13