Dry tribological behavior of a cast Mg-Gd-Zr-Ag alloy at room and elevated temperatures

Abstract

The hardness and wear resistance of cast Mg-6Gd-0.6Zr alloy were increased by the addition of 2 wt.% Ag. The microstructural studies of Mg-6Gd-0.6Zr–2Ag exhibited Ag-containing compounds within the α-Mg matrix. The addition of Ag increased the hardness by 20–30% at various temperatures up to 300 °C. The dry sliding wear behaviors of Mg-6Gd-0.6Zr and Mg-6Gd-0.6Zr–2Ag alloys were investigated under normal loads of 5, 20 and 40 N at wear temperatures of 25–325 °C against 52,100 steel using a pin-on-disk tribometer. Under a normal load of 5 N at various wear temperatures, Mg-6Gd-0.6Zr–2Ag alloy showed a higher wear resistance than Mg-6Gd-0.6Zr. However, under higher normal loads of 20 and 40 N at temperatures of 125–225 °C and 125–175 °C, respectively, the Ag-containing alloy showed a higher wear rate than the base alloy. The results also showed that the wear rates decreased with increasing temperature to critical temperatures of 225 °C for Mg-6Gd-0.6Zr and 275 °C for Mg-6Gd-0.6Zr–2Ag, which were then followed by a rise due to thermal softening and higher plastic deformation of the alloys.

Keywords

• Mg-Gd-Zr-Ag alloy
• Dry sliding wear
• Hardness
• Ag addition