Effect of Ultrasonic Surface Rolling Process on Wear Behavior of Mg-15Gd-1Zn-0.4Zr Alloy

In this study, the effect of ultrasonic surface rolling process (USRP) on the wear behavior of Mg-15Gd-1Zn-0.4Zr (GZ151K, wt.%) alloys was investigated. Results show that the surface morphology and hardness of GZ151K alloy were significantly improved by USRP. After USRP, a gradient twin microstructure on the cross-sectional plane of GZ151K alloy was formed. Comparing with untreated samples, an improved wear resistance of samples after USRP was found due to the gradient twin microstructure strengthening effects. Moreover, the wear mechanism of GZ151K alloy with gradient twin microstructure was transferred from abrasion to abrasion + delamination at 0.01 m/s and the abrasion + oxidation at 0.1 m/s, respectively. Due to the atomic diffusion function of gradient twin microstructure, more MgO patches were observed at the worn surface of USRPed sample under high sliding speed (0.1 m/s) and high applied load (50 N).