Beneficial effects of yttrium on the performance of Mg-3%Al alloy during wear, corrosion and corrosive wear

Magnesium has attracted considerable attention from industry especially from the transportation sector due to its high strength-to-weight ratio. However, poor wear resistance and especially low corrosion resistance of Mg are barriers to extensive use of Mg alloys. Yttrium is one of the rare-earth elements, which has been demonstrated effective in improving the corrosion resistance and tribological properties of some metallic alloys. In this work, effects of yttrium on wear, corrosion and corrosive wear of as-cast Mg-3%Al alloy were investigated. It was shown that the added Y increased the wear resistance of the alloy through the formation of a harder second phase, Al2Y. In the case of corrosion, a small amount of added Y improved the corrosion resistance but such benefit decreased when the yttrium contents was higher than 2 wt%Y. When worn in tap water involving corrosion, yttrium also improved the performance of Mg-3%Al alloy. Possible mechanisms responsible for these changes are discussed.