Effect of Ce addition on the high‐temperature oxidation resistance of Mg–Gd alloys

Abstract

In the present study, the oxidation resistance of magnesium alloyed with Gd and Ce was investigated. The high-temperature oxidation resistance of Mg-3.5Gd-xCe (x = 0, 0.2, 0.4, 0.7 and 1.0 wt%) alloys was evaluated at temperatures between 550°C and 650°C. Results indicate that adding less than 0.7 wt% Ce resulted in high oxidation resistance, whereas the Ce addition exceeding 0.7 wt% deteriorated the oxidation resistance. The high oxidation resistance phenomenon is attributed to the formation of compact oxide films primarily composed of MgO, Gd 2 O 3 , and a small amount of CeO 2 on the surface of Mg-3.5Gd-0.2Ce and Mg-3.5Gd-0.4Ce alloys. These compact oxide films can prevent the matrix from experiencing further oxidation. The deteriorated oxidation resistances of Mg-3.5Gd-0.7Ce and Mg-3.5Gd-1Ce alloys were found to be due to the severe internal oxidation caused by the distributed Mg 12 Ce phases along the grain boundaries.