Wear resistance and electroconductivity in a Cu–0.3Cr–0.5Zr alloy processed by ECAP

Abstract

The ultrafine-grained microstructures and functional properties, including wear resistance for dry sliding and electrical conductivity, were investigated in a Cu–0.3 %Cr–0.5 %Zr alloy processed by equal-channel angular pressing (ECAP) at a temperature of 400 °C to total strains of 1, 2, and 4. Severe plastic deformation by ECAP to a total strain of ~1 led to a significant decrease in the wear resistance because of the rapid surface damage to both solution-treated (ST) and aged (AT) samples where a high density of dislocations was arranged in stochastic low-angle subboundaries by brittle fracture. Further deformation by subsequent ECAP passes promoted the subdivision of the shear bands by geometrically necessary boundaries. Correspondingly, the number of fine crystallites outlined by high-angle boundaries increased, and the wear rate decreased. After four ECAP passes, the wear rate decreased to the level of the initial state of the alloy and equaled 1.68 × 10−5 mm3/(N m) and 1.40 × 10−5 mm3/(N m) for ST and AT samples, respectively. The results demonstrate that the damage mechanism is the controlling factor for wear resistance of Cu–Cr–Zr bronze hardened by intense plastic straining.