Research Progress on the Oxidation Behavior of Ignition-Proof Magnesium Alloy and Its Effect on Flame Retardancy with Multi-Element Rare Earth Additions: A Review

The phenomenon of high-temperature oxidation in magnesium alloys constitutes a significant obstacle to their application in the aerospace field. However, the incorporation of active elements such as alloys and rare earth elements into magnesium alloys alters the organization and properties of the oxide film, resulting in an enhancement of their antioxidation capabilities. This paper comprehensively reviews the impact of alloying elements, solubility, intermetallic compounds (second phase), and multiple rare earth elements on the antioxidation and flame-retardant effects of magnesium alloys. The research progress of flame-retardant magnesium alloys containing multiple rare earth elements is summarized from two aspects: the oxide film and the matrix structure. Additionally, the existing flame-retardancy models for magnesium alloys and the flame-retardant mechanisms of various flame-retardant elements are discussed. The results indicate that the oxidation of rare earth magnesium alloys is a complex process determined by internal properties such as the structure and properties of the oxide film, the type and amount of rare earth elements added, the proportion of multiple rare earth elements, synergistic element effects, as well as external properties like heat treatment, oxygen concentration, and partial pressure. Finally, some issues in the development of multi-rare earth magnesium alloys are raised and the potential directions for the future development of rare earth flame-retardant magnesium alloys are discussed. This paper aims to promote an understanding of the oxidation behavior of flame-retardant magnesium alloys and provide references for the development of rare earth flame-retardant magnesium alloys with excellent comprehensive performance.