Effect of Zn addition on the oxidation property of Mg-Y alloy at high temperatures

Abstract

The effect of Zn addition on oxidation behavior of Mg-3Y alloys at 500 °C and 530 °C in the dry air was investigated. The alloy with 2.5 wt% Zn addition showed the best oxidation resistance of all. A dense and compact Y2O3/MgO composite oxide film was formed on the surface of Mg-3Y-2.5Zn alloy after oxidation. In addition, the concentration of Y element in the oxide film of Mg-3Y-2.5Zn alloy was found to have a relatively high level among the test Mg-Y-Zn alloys. The results show that the appropriate addition of Zn (1–2.5 wt%) was beneficial to the enrichment of Y element in the oxide film. However, excessive addition of Zn (3.5 wt%) caused the decrease of Y content and the formation of ZnO in the oxide film, which would deteriorate the oxidation resistance of Mg-Y alloy. The concentration of Y2O3 increased from the outmost to the inner layer in the oxide film of Mg-3Y-2.5Zn and Mg-3Y-3.5Zn alloys, and the content of MgO (MgCO3/Mg(OH)2) slightly reduced from the substrate surface to inner layer. ZnO mainly existed in the outside layer in the oxide film of Mg-3Y-3.5Zn alloy.