High-temperature oxidation behavior and corrosion behavior of high strength Mg-xGd alloys with high Gd content

Highlights: • The magnesium alloy with high Gd content forms dense multilayer oxide film at high temperature. • The Multilayer film is composed of cubic phases, MgO and Gd₂O₃ from inside to outside. • High content of Gd improves the corrosion resistance of magnesium alloy. • Mg₅Gd phase forms a sacrificial anode and plays a cathodic protection role. Three alloys of Mg-0Gd, Mg-13Gd-0.5Zr and Mg-20Gd-0.6Zr (wt%) are smelted to study the effect of high Gd content on the high-temperature oxidation and corrosion behavior. Results show that with the increasing content of Gd, the high-temperature oxidation resistance and corrosion resistance increase. Oxide film is divided into three layers. The outermost layer is Gd₂O₃ and a small amount of ZrO₂, the middle layer is MgO and the bottom layer is the cubic phases (Gd, Zr)H₂. The pitting depth of Mg-20Gd is 1/6 that of Mg-0Gd, forming a sacrificial anode and playing a cathodic protection role.