W、B、Y微合金化高铌TiAl基合金高温抗氧化性研究

使用元素W、B、Y对Ti-45Al-8Nb合金进行了微合金化,研究了微合金化后高铌TiAl基合金在900℃静止空气中的断续氧化行为。结果表明,与Ti-45Al-8Nb合金相比,经过0.2B与0.1Y联合微合金化后合金的氧化增重小,氧化膜与基体的粘附性强,抗氧化性明显改善;经过0.2W与0.1Y微合金化后合金氧化增重明显,氧化膜容易脱落,合金抗氧化性下降;经过0.2B、0.2W、0.1Y联合微合金化后合金抗氧化性没有明显变化。对氧化膜进行的扫描电镜(SEM)、能谱分析(EDS)及X射线衍射(XRD)分析表明,联合添加B、Y促进了合金中的连续致密的Al2O3条带的形成,W、Y联合微合金化的合金中靠近基体处未形成连续的Al2O3条带,并且混合层中形成了较厚的低铌含量的TiO2层。W、B、Y联合微合金促进了混合层中富Al2O3层的形成。

High-Temperature Oxidation Resistance of W, B, Y Microalloyed TiAl Based Alloys with High Nb Content

The interrupted oxidation behavior of B, W and Y micro-alloyed TiAl-based alloys with high Nb content at 900 oC in static air was investigated. The results show that the combined addition of 0.2wt%B and 0.1wt%Y improves the oxidation resistance obviously with less oxidation weighting and enhanced adherence of the oxide scale, while the combined addition of 0.2wt%W and 0.1wt%Y leads to poor oxidation resistance with higher oxidation weighting and impairing adherence of the oxide scale. Besides, the oxidation resistance of the alloy with combined addition of 0.2wt%B, 0.2wt%W and 0.1wt%Y does not change significantly. Oxidized samples were examined by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction analysis (XRD). It is found that the combined addition B and Y can promote the formation of continuous and compact Al2O3 oxide scale. The combined addition W and Y produces continuous Al2O3 layer near to the matrix and thick TiO2 layer with low Nb content in the mixed layer. Combined addition W, B and Y promotes the formation of Al2O3 oxide scale in the mixed layer.