添加Si及Al對Si合金高溫氧化行為之影響

Effect of Si and Al Additions on the High-Temperature Oxidation Behavior of Si- based Alloys

本研究主要探討Ti5Si3及TiSi2及(TiSi2)91Al9合金在800 ~ 1000℃之空氣氧化行為研究。整體而言，三種合金在800 ~ 1000℃之氧化動力學皆遵守拋物線，顯示其氧化反應由固態擴散來主導。此外，三種Ti-Si-Al合金的氧化速率常數（kp）皆隨溫度升高而增加，但隨Si含量增加而降低。比較兩種Ti-Si合金氧化速率後，可知Si含量的增加能改善其抗氧化能力。另一方面，(TiSi2)91Al9合金氧化後的主要氧化生成物為α-Al2O3，可知它的生成有助於進一步地提升Ti-Si合金的抗氧化能力。

The oxidation behavior of Ti5Si3, TiSi2, and (TiSi2)91Al9 alloys was studied over the temperature range of 800 ~ 1000 ℃ in dry air. In general, the oxidation kinetics of the three alloys followed the parabolic-rate law, indicating that diffusion was the rate-determining step during oxidation. The oxidation rate constants (kp values) gradually increased with increasing temperature but decreased with increasing Si content. It was found that the addition of Si content can improve the oxidation resistance of Ti-Si alloy. In addition, the scales formed on the (TiSi2)91Al9 alloy consisted mostly of α-Al2O3, of which the formation was responsible for the further improvement on oxidation resistance.