Grain-Boundary Sliding in Zinc Bicrystals Deformed at a Constant Strain Rate

Abstract

Zinc bicrystals have been deformed at a constant rate of overall shear between 20 and 375° C. The specimens were gripped in such a way that basal slip was forced to interact with the grain boundary and throughout each test the grain-boundary shear displacement was compared with the overall specimen deformation behaviour. Aspects of the sliding behaviour were found to be in accordance with a dislocation glide–climb model for the basic mechanism of sliding. The extent of sliding was controlled by a slide-hardening process that took place in the immediate vicinity of the grain boundary at a constant rate during each test. This behaviour was reflected as a linear relationship between the sliding displacement and the shear stress developed. The sliding was related to crystal deformation through its effect on the overall shear stress achieved during testing. Information on the processes controlling slide-hardening was obtained from its temperature-dependence.