Stacking fault energy measurement from diffusion

The annealing kinetics of dislocation loops has been considered from climb theory based on a model involving vacancy diffusion as the rate controlling mechanism. The theory has been applied to fee metals of high, intermediate, and low stacking fault energy to determine both the intrinsic and extrinsic fault energy using transmission electron microscopy. Reliable values are obtained from metals with γ ? 70 erg per sq cm but for low γ metals the rate controlling mechanism is shown to be one of jog nucleation and propagation rather than vacancy diffusion. The technique of loop annealing is also shown to be applicable to hep metals such as zinc, magnesium, and cadmium, even when the foil surfaces act as vacancy sources. Results of loop shrinkage and loop growth are analyzed to provide fault energy values for those metals with hep structure.