Enhancing the strength and conductivity of commercialized Cu-Cr-Zr plate through simple high strain cold rolling and aging

Abstract

Plastic deformation usually improves the strength of Cu alloys by introducing high density dislocations and refined grains, but inevitably reducing electrical conductivity and ductility. Here we demonstrate that three exclusive properties, i.e., strength, conductivity, and ductility can be simultaneously enhanced in commercialized Cu-Cr-Zr plates through the well-controlled thermomechanical treatment. Very high strain cold rolling with a thickness reduction of 98% is applied, resulting in the formation of ultra-fine lamellar structures with an average size of 146 nm, which contributes to high tensile strength of 643 MPa. However, the elongation and electrical properties are poor. The subsequent aging treatment at a low temperature of 400 °C for 5 h introduces high density coherent Cr precipitates in those lamellar structures, while keeping the lamellar thickness almost unchanged. The aged Cu-Cr-Zr alloy exhibit high strength of 592 MPa, high conductivity of 86.8% IACS, and adequate elongation of 15.5%. This work proposes a strategy of overcoming the strength-ductility and strength-conductivity trade-off relationships in industrial Cu products through the balanced manipulation of grain morphology and grain interior precipitation.