Microstructures and properties of ultrasonically surface-modified Cu–0.2Be–1.0Co alloy

Abstract

ABSTRACT Low-Be copper alloys exhibit high thermal and electrical conductivities but weak strength, hardness, wear and corrosion resistances, which limit their practical applications severely. To overcome these defects, we herein systematically investigate the effects of ultrasonic surface modification on the microstructures and properties of Cu–0.2Be–1.0Co alloy. It is found that the gradient microstructures characterized by pile-ups and dents, fine grains, dense dislocations and compressive residual stresses are generated in the 171 μm thickness surface layer of the Cu–0.2Be–1.0Co alloy by ultrasonic surface modification. As a result, the surface hardness obtains a 162% enhancement, the wear rate drops from 5.03 × 10−4 to 3.46 × 10−4 mm3·N−1·m−1, and the electrochemical corrosion current density decreases from 3.24 to 1.92 μA/cm2. These results indicate that the comprehensive properties of Cu–0.2Be–1.0Co alloy can be simultaneously improved by utilizing ultrasonic surface modification.