Diffusional coherency strain theory, and its implications for the chemically induced migration of liquid films and grain boundaries, were reviewed. It was suggested that critical experiments on metals and oxides had demonstrated the validity of this theory. The observed characteristics of this phenomenon (presence of misfit dislocations at the initial boundary location, migration direction, faceting, dependence upon grain-boundary structure, effect of boundary curvature, effect of temperature) were considered to be consistent with coherency strain theory. Other theories tended to be largely inconsistent with observations, and there was little experimental evidence of their validity. There was also experimental evidence that coherency strain theory was applicable to discontinuous precipitation.

D.Y.Yoon: International Materials Reviews, 1995, 40[4], 149-79