中文摘要：

研究了0．8％La2O3-MosSi3／MoSi2复合材料在1200℃空气中的高温氧化行为。结果表明：0．8％稀土和MoSi3的加入，使材料的抗氧化性能降低。MosSi3含量越高，材料的抗氧化性能越差。当MosSi3含量低于30％时，在氧化初始阶段，质量变化呈直线下降，随着氧化的进行，氧化逐渐增重，材料表面形成较致密的SiO2阻止了材料的进一步氧化，使得氧化增重较小。而0．8％La2O3-40％Mo5Si3／MoSi2复合材料却出现了“粉化”现象。0．8％La2O3．MosSi3／MoSi2复合材料抗氧化性能的降低，归因于Mo5Si3差的抗氧化性和材料致密度的降低；另外，稀土和Mo5Si3的加入，细化了材料的晶粒，使晶界面积增加，加速了氧在晶界中的扩散，促进了材料的氧化。

英文摘要：

The oxidation behavior of 0. 8% La2O3- Mo5Si3/MoSi2 composites at 1200℃ in air was investigated. The results reveal that the oxidation resistance of the material with 0.8% La2O3 and Mo5Si3 is impaired. The oxidation resistance is decreased with increasing Mo5Si3 content. The mass loss follows a linear law in the initial oxidation. With oxidation time prolonging, a continuous and dense oxidation scale prevents oxygen from diffusing and leads to mass change a little increasing when the Mo5Si3 content is less than 30%. However, the composite shows ＂PEST＂ withthe addition of 40% MosSi3. With increasing Mo5Si3 content, the oxidation resistance of 0.8% La2O3-Mo5Si3/MoSi2 decreases. This attributes to the poor oxidation resistance of Mo5Si3 and the relative density decreasing of 0.8% La2O3-Mo5Sia/MoSi2 composite. In addition, the addition of rare earths and Mo5Si3 to MoSi2 reduces the average grain size, which increases the grain boundary area. The reduction in the grain size is generally accompanied by acceleration of diffusion speed of oxygen and promotion of material oxidation.