Tribological Characteristics of Mg–3Al–0.4Si–0.1Zn Alloy at Elevated Temperatures of 50–200 °C

The tribological characteristics of Mg–3Al–0.4Si–0.1Zn alloy were investigated within a load range of 20–360 N and at test temperatures of 50–200 °C using a pin-on-disk configuration. An empirical wear transition map has been established to delineate the effects of applied load and test temperature on wear mechanisms in the mild and severe wear regimes. The microstructural evolution and hardness change in subsurfaces revealed that it was the microstructural transformation from the plastic deformed to the dynamic recrystallization (DRX) that caused the softening of the surface layer material at temperatures of 50–200 °C. At 200 °C, the structure of friction-affected zone (FAZ) was quite different from that at temperatures of 50–150 °C; a static recrystallization sub-zone occurred due to the test temperature in excess of the static recrystallization temperature of the alloy. The FAZ consisted of plastic deformation, static recrystallization and plastic deformation sub-zones in the mild wear regime, and DRX, static recrystallization and plastic deformation sub-zones in the severe wear regime. The mild-severe wear transition still follows the contact surface DRX temperature criterion within the temperature range of 20–200 °C, and the transition loads can be evaluated as a function of test temperature using the criterion.