Preparation of layered gradient Cu–Cr–Ti alloy with excellent mechanical properties, thermal stability, and electrical conductivity

Abstract

Abstract Cu–Cr–Ti alloy with gradient properties was prepared at 960°C for 2 h in air, 80% cold rolling, and then aging at 500°C for 1 h. The results showed that the surface layer of Cu–Cr–Ti alloy had achieved a good match of electrical conductivity (96.2% International Annealed Copper Standard (IACS)), thermal stability (softening temperature of 650°C), and wear resistance (friction coefficient of 0.17). Meanwhile, the core region maintains high tensile strength (519 MPa) and good electrical conductivity of 71.8% IACS. Transmission electron microscope characterization revealed that the precipitates of surface layer are composed of Cr oxides, complex oxides formed by Cu, Cr, and O, and Ti-rich phases. The existence of oxide particles with discontinuous distribution and stable properties is the reason for the good electrical conductivity, excellent thermal stability, and outstanding wear resistance of the surface layer. The main precipitates of the core are Cr. The high tensile strength of the core is ascribed to the aging strengthening effect of these fine Cr particles. This work provides ideas and approaches for the preparation of copper alloy with excellent properties for high-speed railway contact wire, and solves the drawbacks of composites synthesized from heterogeneous materials.