Effect of ultrasonic shot peening on microstructure and properties of Cu-Ti alloy

Modified surface layers with refined grain size and high microhardness characteristics were prepared on Cu-Ti alloy using ultrasonic shot peening (USP) by controlling the shot diameter. The phase structure and organization morphology of the modified layer were analyzed using x-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscope (SEM). The microhardness, wear resistance and corrosion resistance were systematically characterized. The results showed that the comprehensive surface properties of the sample was optimized at a shot diameter of 3.0 mm. The average grain size was refined to 12.4 nm under the high-frequency impact of steel balls. Owing to the grain refinement and work hardening, the surface microhardness, wear resistance and corrosion resistance of the sample was significantly improved. Among these, the surface microhardness of the sample was enhanced from 257.68 HV0.1 to 313.51 HV0.1, the volume wear rate was decreased from 0.3305 um(2) N-1 to 0.1707 um(2) N-1, and the self-corrosion current density was also decreased from 1.658 x e(-5) mA mu m(-2) to 4.053 x e(-6) mA mu m(-2). It is proved that USP is one of the effective methods for preparing Cu-Ti alloys with excellent surface properties.