High-resolution in situ observation of moving grain boundaries in gold by high-resolution electron microscopy

Abstract

Structural changes of the grain boundaries in gold was observed in situ by high-resolution electron microscopy. In one case a large-angle grain boundary without any apparent periodic structure became periodic as one of the component crystals rotated with respect to the other by about 7[ddot] and the boundary migrated to assume a {111}_A ‖ {111}_B Σ = 3 coincidence orientation relationship (i.e. coherent twin). A similar coherent twin was nucleated at the corner of a bent grain boundary as the boundary migrated away, leaving behind an increasing length of the coherent twin.