Effects of Load on Dry Sliding Wear Behavior of Mg–Gd–Zn–Zr Alloys

Dry sliding wear tests on as-cast and T6-treated Mg-3Gd-1Zn-0.4Zr（wt%, GZ31K） and Mg-6Gd-1Zn-0.4Zr（wt%, GZ61K） alloys were performed using a ball-on-disk configuration at room temperature. Friction coefficient and wear rate of the alloys were measured under three different applied loads（50 N, 100 N, and 200 N, respectively）. Worn surface morphologies were analyzed using a scanning electron microscope（SEM） coupled with an energy dispersive spectrometer（EDS）. It is found that the friction coefficient of the alloys decreases with increasing load, except the as-cast GZ61 K. The wear rates of the as-cast Mg-Gd-Zn-Zr alloys increase with the increase of the load. However, the wear rates of the T6-treated Mg-Gd-Zn-Zr alloys first increase because of the participation of a large amount of needle-like precipitates, but then decline due to obvious work hardening. The wear mechanisms of abrasion, plastic deformation, oxidation, adhesion and delamination are detected. Abrasion dominates the wear mechanism under the low load; whereas, adhesion is the main wear mechanism under intermediate load, and plastic deformation has great effect on the wear rate under high applied load.