The work-hardening of copper-silica

Abstract

As a preliminary to describing the dislocation distribution in deformed alloys of copper containing a small volume fraction of SiO₂ particles, the stress distribution in such an alloy is calculated on the assumption that no plastic relaxation takes place around the particles. The continuum approximation is used, and it is shown that apart from local fluctuating stresses the image stress—that is, the stress which arises because the specimen has stress-free external surfaces—contributes a uniform back stress approximately given by the shear modulus times the plastic strain times the volume fraction of particles. It is shown that the image stress dominates the work-hardening of the material at large plastic strains.