Deformation induced precipitation in CuCrZr composites

Abstract

In this study, we enhanced both hardness and electrical conductivity in solution-treated Cu-0.66Cr-0.05Zr (at%) wires. After cold deformation, hardness increased by ∼100%, and electrical conductivity increased by 24%. We further demonstrated that post-deformation aging increased hardness by another 27%–38% and electrical conductivity by up to an additional 80%. In previous research on composite conductors, hardness increase by deformation was usually accompanied by a decrease in electrical conductivity. But we were able to increase both simultaneously by controlling thermo-mechanical process parameters to engineer precipitate size and density. We attributed our simultaneous enhancement of hardness and conductivity to the generation of deformation-induced, disc-shaped, and semi-coherent precipitates with thicknesses less than a nanometer. Aging-induced precipitates remained only a couple of nanometers thick, but their Cr content (1.2–8.4 at%) was relatively greater than that of deformation-induced precipitates. We subjected solution-treated materials to either aging followed by deformation or deformation followed by aging. Our results were the same regardless of order.