Grain boundary migration during abnormal grain growth in nanocrystalline Ni

The transformation mechanisms of abnormal grain growth in nanocrystalline Ni were studied extensively by transmission electron microscopy (TEM). A combination of in situ TEM annealing and ex situ annealing followed by TEM characterization was used. It was observed that grain boundary migration is both spatially and temporally non-uniform; migration occurs in a series of discrete steps, which are followed by periods of stagnation.