The Tensile Deformation of Solute-Strengthened Copper Polycrystals

Abstract

The rate of solution-hardening derived from. the flow stresses at 1% strain extrapolated to infinite grain size, and details of the transition from elastic to plastic flow, are considered for copper-base alloys. Solutes may be divided into two classes: weak and strong hardeners, depending on their relative contributions to solution-hardening. Solutes in the stronger-hardening class induce yield points that show the normal dependence on grain size and temperature, whereas the yield points of the other alloys usually become less sharply defined with decreasing temperature or grain size. In all alloys there was an approximately linear increase in flow stress with solute concentration at low solute contents. The rates of solution-hardening were not entirely consistent with any of the existing interaction parameters. The original Mott–Nabarro relationship comes closest to that observed experimentally, with the exception of copper–silicon alloys. A single relationship between flow stress at room temperature and that extrapolated to 0 K suggests that the same processes are responsible for the thermal and athermal contributions to the solute-strengthening.