The effect of dispersed phases upon the annealing behaviour of plastically deformed copper crystals

Abstract

An electron microscopic investigation is described of the effect of high temperature annealing on deformed copper single crystals containing dispersed second phases of either cobalt or silica. Sections of selected orientation cut from the deformed crystals were annealed at 700°C. It was found that specimens deformed into Stage I recovered to the low dislocation densities present before deformation, whereas the crystals deformed to Stage II recovered to form structures consisting of sheets of dislocation networks on the primary slip planes. Several of the basic networks were analysed, and their formation and distribution are discussed in terms of a modification of the deformation structures. Annealing at temperatures at which the cobalt precipitate redissolved resulted in little further structural change. The ability of these crystals to resist recrystallization is ascribed to the stability of the recovered structures and the absence of suitable recrystallization nuclei, arising from the increased homogeneity of the dislocation distribution observed in the deformed state.