Fabrication of Gradient Microstructure for Enhancing Wear Resistance of Mg‐1.9Mn‐0.3Ce Alloy via Ultrasonic Surface Rolling Process

The strengthening mechanism on wear behavior of Mg‐1.9Mn‐0.3Ce alloy subjected to surface rolling process (USRP) under different sliding speeds and applied loads is investigated in this study. The wear rates and coefficient of friction (COF) values of Mg‐1.9Mn‐0.3Ce alloy after USRP are both reduced. In particular, at a sliding speed of 0.02 m s −1 and 10 N load, the COF and wear rate of the USRP‐treated sample are ≈19% and 74% lower than those of the untreated sample. At a low sliding speed (0.02 m s −1 ), the wear behavior of untreated samples transitioned from fatigue wear to a mix of abrasive and delamination wear with increasing applied load. In contrast, the worn surface of samples treated by USRP retained fatigue wear characteristics while showing milder delamination and abrasive wear at higher applied loads. At a high sliding speed (0.2 m s −1 ), the wear resistance of Mg‐1.9Mn‐0.3Ce alloy is also improved with varying applied loads, although the wear mechanism is not significantly changed compared to the untreated sample. The improved wear behavior of Mg‐1.9Mn‐0.3Ce alloy after USRP is primarily attributed to the strengthening effect by the modified microstructure and the inhibiting effect of crack initiation and propagation enabled by the gradient microstructure.