Abstract: Microstructure, microhardness, friction coefficient, wear rate and worn surface morphology of solution treated Mg-xGd-1Zn-0.4Zr (x=3, 6, 9 wt%) alloys with different Gd contents and solution treated Mg-6Gd-yZn-0.4Zr (y=0.5, 1, 2 wt%) alloys with various Zn additions were studied by means of optical microscope, scanning electron microscope, energy spectrometer, microhardness tester and friction and wear testing machine. The results show that the grains refine, the microhardness increases, and the friction coefficient shows slight change with Gd or Zn content increasing. The wear rate of the alloys increases slightly with the increase of Gd content, whereas, it decreases with the increase of Zn content. Compared with the alloy containing 0.5%Zn, the wear rate of the alloy containing 2%Zn presents 24% reduction. The main wear mechanisms of the five alloys are abrasion, oxidation and plastic deformation, as well as adhesion for the alloy containing 9%Gd. The wear resistance of the alloys depends on the wear mechanisms and has no direct relation to the hardness.

Key words: Mg-Gd-Zn-Zr magnesium alloys, friction coefficient, wear rate, wear mechanism