A high-index (S = 51b) coincidence-site lattice grain boundary in 4wt%Mg alloy was investigated by means of high-resolution electron microscopy. The specimen had been strained to 3% in tension. Because the grain boundary was of incidental high-index coincidence-site lattice type, its structure and properties often resembled those of a general grain boundary in a deformed polycrystalline material. The boundary could be divided into symmetrical and asymmetrical sections. Periodic boundary structures were seen in both parts. Grain-boundary migration, due to irradiation or heating, was observed in situ as a result of ledge motion along the boundary. This supported the Gleiter model of grain-boundary migration via a step mechanism.

In situ High-Resolution Electron Microscopy Observation of Grain-Boundary Migration through Ledge Motion in an Al-Mg Alloy. S.G.Song: Philosophical Magazine Letters, 1999, 79[8], 511-7