添加Al對MoSi2合金高溫氧化行為之影響

Effect of Al Addition on the High Temperature Oxidation Behavior of MoSi2 Alloys

本研究探討添加少量的Al對MoSi2合金在700 ~ 1000℃之高溫氧化行為。整體而言，MoSi2合金在700℃以上易形成揮發性MoO3，產生嚴重的氧化失重。添加少量Al的Mo-Si-Al三元合金，氧化動力學遵守抛物線律且有氧化增重，明顯地改善MoSi2合金之揮發特徵。由顯微結構分析得知，氧化後三合金表面主要的氧化生成物為α-Al2O3，因而有助於提升合金的抗氧化能力。

The effect of Al addition on high temperature oxidation behavior of MoSi2 was studied over the temperature range of 700 ~ 1000 ℃. In general, the MoSi2 alloy generated a volatile species of MoO3 during oxidation above 700 ℃, while the oxidation kinetics of the Al-added ternary alloy followed the parabolic-rate law, and the volatilization of MoO3 was significantly reduced. Based on microstructural analyses, the scales having formed on the (MoSi2)95Al5 surface consisted mostly of α-Al2O3, of which the formation led to an improvement of oxidation resistance in this alloy.