Deformation behavior during low-temperature rolling and the multi-scale evolution mechanism of macro and microstructures in CuCrZr alloy

Abstract

To address the insufficient ductility of CuCrZr copper alloy under the simultaneous demands for high strength and high electrical conductivity, we propose a process strategy that combines dual gradient temperature controlled rolling with aging treatment to comprehensively optimize the alloy’s performance. This approach alternates rolling at room and cryogenic temperatures, induces nanoscale twinning during low temperature deformation, and leverages the temperature gradient to tailor the alloy’s microstructure, thereby enhancing its overall properties. After the cryogenic deformation process, the alloy reached an ultimate tensile strength of 387.5 MPa, an electrical conductivity of 84.6% IACS, and an elongation of 12.45%. The results demonstrate that, compared with room temperature rolling, the dual low temperature rolling process more effectively refines grain size, significantly strengthens the S and Brass texture components, and induces nanoscale twinning while also promoting a uniform distribution and high volume fraction of nanoscale precipitates. Crucially, the high density dislocation rearrangement triggered during cryogenic rolling together with twin boundaries that serve as dislocation slip pathways effectively alleviates local stress concentrations and thus significantly improves the alloy’s ductility. Furthermore, quantitative analysis of various strengthening mechanisms shows that the increase in yield strength is primarily attributable to grain boundary strengthening and precipitation strengthening, while the substantial residual dislocation density remaining after secondary aging further reinforces the overall strengthening effect.