Oxidation resistance of Mg-Gd-Y-Zn-Mn alloy under flame exposure

In order to expand the application of magnesium alloys in some extreme environments, the oxidation resistance under flame exposure of Mg-10Gd-5Y-2Zn-1Mn alloy was studied in this paper. Some results on oxidation resistance, O content changes in phases, evolution of oxide film, and microstructure are obtained. The average ignition time of Mg-10Gd-5Y-2Zn-1Mn alloy under flame exposure is 45.3 s, indicating the high oxidation resistance of the alloy. The oxidation of second phases is dominant initially. As the temperature increases, Y and Gd in α-Mg continuously diffuse outward, resulting in severe oxidation of α-Mg. While the diffusion of atoms in second phases with good high-temperature stability is relatively difficult. With the temperature rising, more Y element diffuses outward to form a dense Y-Gd-O oxide film. However, the high Mg vapour causes small cracks on the oxide film, resulting in the ignition. These findings provide a theoretical basis for the design of Mg alloys in high-temperature environments.