元素Si对TiAl合金抗氧化性能的影响

研究了元素Si对不同Nb含量TiAl合金抗氧化性能的影响．结果表明，合金中Nb含量越低，Si对合金抗氧化性能的提高作用越明显．主要表现为Si促使二元合金形成连续致密的Al2O3层及使不同Nb含量合金表层氧化物更加均匀细小．因而随Si含量的增加，TiAl合金的氧化增重速率系数降低，氧化速率下降．运用等温氧化增重实验、X射线衍射和扫描电镜等手段对Si的作用进行了分析讨论．

EFFECTS OF ELEMENT Si ON OXIDATION RESISTANCE OF TiAl ALLOYS

The effects of alloying element Si on oxidation resistance of several 7-TiAl based alloys containing different Nb contents have been studied. The results reveal that the lower the Nb content of the alloy, the more obvious the beneficial effect of Si. The improvement of oxidation resistance by Si is mainly attributed to promoting the formation of continuous and dense Al2O3 layers in the binary alloy. In addition, more homogeneous and finer oxidation products appear on the surface of higher Si-bearing alloys than on lower Si-bearing alloys, leading to further improvement of oxidation resistance in Nb-containing alloys. As a result, the parabolic rate constant decreases with increasing Si content. Isothermal oxidation experiment, X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis of the oxidation products are presented.