The effect of the existing state of Y on high temperature oxidation properties of magnesium alloys

Abstract

This paper studies the effect of the existing state of Y element on the high temperature oxidation resistance of magnesium alloys. Different levels of Al element were added into Mg–2.5Y alloy to obtain different existing state of Y. The oxidation rate of Mg–2.5Y–2.5Al alloy is the highest among Mg–2.5Y, Mg–2.5Y–2.5Al and Mg–2.5Y–4.2Al alloys at 500°C. An effective and protective Y2O3/MgO composite oxide film was formed on the surface of Mg–2.5Y alloy after oxidized at 500°C for 360min. The results show that the dissolved Y element in the matrix was beneficial to improve the oxidation resistance of magnesium alloys. Once Y element transformed to the high temperature stable Al2Y compound, its ability in preventing oxidation would disappear. The formation of Al2Y compound severely deteriorated the oxidation resistance of Mg–2.5Y alloy. In addition, the dissolved Al can also cause the rise of oxidation resistance at a certain extent.