Tribological behavior of AZ91D magnesium alloy at elevated temperatures

摘要

The wear behavior of AZ91 magnesium alloy was investigated under applied loads of 5, 20 and 40 N at the wear testing temperatures of 25℃ to 300℃. The wear tests were carried out using a pin-on-disk tribometer at a sliding speed of 0.4 ms~(-1) for a total sliding distance of 1000 m. The examination of worn surfaces showed that the abrasive wear was the main mechanism at 25℃ under the loads tested. The results showed that under a normal load of 40 N, rising the wear temperature increased the wear rate. However, under a normal load of 20 N the wear of the alloy decreased by about 58% as the wear temperature increased to 100℃. Further increase in the wear temperature to 250℃ resulted in an increase in the wear of the alloy due to the softening and dissolution of β-Mg_(17)Al_(12) phase. Under a normal load of 5 N, the wear rate decreased as the wear temperature increased to 250℃. Under a specific normal load, there was a critical surface temperature at which a transition from a mild to a severe wear mechanism might occur. These temperatures were about 140, 180, and 400℃ at the normal loads of 40, 20, and 5 N, respectively.