Investigation of temperature-induced wear transition of an Mg-10Gd-1.4Y-0.4Zr alloy under non-lubricated sliding conditions

The friction and wear behavior of an Mg-10Gd-1.4Y-0.4Zr alloy were investigated in detail within a temperature range of 20-200oC in order to clarify temperature-induced mild-severe (M-S) wear transition mechanism and verify if contact surface dynamic recrystallization (DRX) temperature criterion can be applicable to elevated temperature M-S wear transition. Coefficient of friction (COF) and wear rate (WR) were plotted against applied load at each test temperature, from which M-S wear transition loads were identified. A wear mechanism transition map was created on test temperature-applied load coordinate system, in which the mild wear region i.e. a safe working region in engineering application was indicated. The M-S wear transition mechanism was proved to be DRX softening by microstructural examination and hardness measurement in subsurfaces. The effects of precipitation and static recrystallization (SRX) occurred at temperatures of 150-200oC on M-S wear transition were also assessed. According to surface DRX temperature criterion, the transition loads were calculated at temperatures of 20-200oC, and the results identified applicability of the criterion to wear tests at elevated temperatures.