The purpose of the present work was to identify the atomic-scale grain boundary migration mechanism and investigate its dependence upon grain boundary structure. High-angle tilt and general grain boundaries were investigated at elevated temperatures using high-resolution transmission electron microscopy in Au and Al bicrystalline thin films. Digital analysis of high-resolution transmission electron microscopy video recordings was used to detect atomic-scale structural changes at migrating grain boundaries. The grain boundary motion was typically not smooth, but involved sharply varying speeds and thermally activated spatial fluctuations. Collective effects in grain boundary migration were shown to exist, and several different migration mechanisms were identified. Atomic-scale grain boundary migration was found to depend upon the macroscopic grain boundary geometry as well as upon details of the interatomic interactions.

In situ HREM Studies of Grain Boundary Migration. K.L.Merkle, L.J.Thompson, F.Phillipp: Interface Science, 2004, 12[2-3], 277-92