In order to develop the ignition-proof magnesium alloy,the effect of alloying elements,Ca and Y,on the oxidation behavior of AZ91 magnesium alloy at elevated temperatures was investigated. The ignition-proof performance,oxide products and oxidation kinetics of Ca-and Y-containing AZ91 alloys were studied. The results indicate that the proper addition of Ca can increase the ignition point of AZ91 alloy greatly. However,the oxide film of Ca-bearing AZ91 alloy formed at elevated temperature is thick and brittle,which is prone to crack in melting and cooling process. In addition,the oxide film of AZ91-xCa alloy is incompact and cannot inhibit the diffusion of reaction particles. The oxide film of AZ91-xCa alloy turns to thin and plastic one after Y is added,and the density of the oxide film increases greatly due to the formation of composite oxide film composed of MgO,CaO and Y2O3.
通过给镁中添加稀土元素 Y 和 Ce 获得了具有良好阻燃效果的 Mg-Y-Ce 合金,该合金能在 1 173 K 的高温下暴露于大气中 0.5 h 而不燃烧。扫描电镜和 X 射线衍射分析表明,合金表面生成了具有双层结构的复杂氧化膜:其中外层主要由 Y2O3和 MgO 组成,内层则由大量的金属镁和极少量的 MgO,Y2O3组成。高温氧化动力学研究显示,该合金在673 K 和 773 K 时氧化符合抛物线-直线规律,而在 873 K 下则遵循四方规律。
