Improved wear resistance of biodegradable Mg–1.5Zn–0.6Zr alloy by Sc addition

Abstract

Magnesium alloys exhibit significant potential for use in next-generation biodegradable materials. Implanted magnesium alloys are expected to exhibit good wear resistance. In this work, the effects of rare earth metal Sc on the wear resistance of biodegradable magnesium alloys were studied. The average grain sizes of Mg–1.5Zn–0.6Zr–xSc (ZK21–xSc, x = 0, 0.2, 0.5, 1.0; wt%) alloys decreased with Sc content increasing. Unlike other rare earth metals, the grain refinement mechanism of Sc belongs to the heterogeneous nucleation mechanism. The yield tensile strengths and Vickers hardness of the ZK21–xSc alloys markedly improved with the addition of Sc increasing. This could be due to the grain refinement and enhanced bond energy resulting from Sc addition. Moreover, the friction and wear tests showed that the friction coefficient of the alloys decreased and the weight loss reduced with Sc addition increasing. This implies that Sc addition could enhance the wear resistance of magnesium alloys. With the addition of Sc increasing, the peeling phenomenon weakened gradually and the worn surfaces of samples became smoother. The major wear mechanisms of the as-cast ZK21–xSc alloys were abrasion wear and delamination wear.