Thermodynamics of faceting Σ3 grain boundaries in Cu

The specific energy γ b of a grain boundary generally depends not only on the misorientation of the adjacent grains but also on the grain boundary plane inclination. That is why a single grain boundary between grains of fixed misorientation is not necessarily planar or smoothly curved. It may facet to minimize its free energy. We have observed grain boundary facets forming at initially planar Σ3 grain boundaries in diffusion-bonded Cu bicrystals. The facets were characterized crystallographically by metallographic methods. The tendency to form facets and the morphology of the facets vary in a characteristic way with the initial grain boundary inclination