Effect of test temperature on dry sliding wear behavior and mild-severe wear transition of Mg97Zn1Y2 alloy

The dry sliding wear behavior of Mg97Zn1Y2 alloy at elevated temperatures was investigated within 50 °C-250 °C under several constant applied loads. Wear rates were plotted as a function of test temperature, and wear mechanisms were identified by examination of worn surfaces using scanning electron microscope (SEM) and energy dispersive x-ray spectrometer (EDS). A wear transition map at elevated temperatures was established on applied load versus test temperature. The microstructures and hardness distributions in subsurfaces were analyzed to identify the predominant mechanism for mild-severe wear transition at elevated temperatures. It was found that with increasing test temperature, the applied load for mild-severe wear transition decreased, and the applied load showed an almost linear relationship with the critical test temperature at mild-severe transition state. The dynamics recrystallization (DRX) microstructure transformation and consequent softening in subsurfaces were the dominant reason for mild-severe wear transition at elevated temperatures. The linear relationship between applied load and test temperature at mild-severe wear transition state followed the contact surface DRX temperature criterion. The linearly fitted critical contact surface DRX temperature was very close to the calculated one using DRX dynamics. The critical loads for mild-severe wear transition at various test temperatures were calculated using the criterion, and they were in good agreement with the measured ones.