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设计了铌当量约为8at%的3种成分合金:Ti-45Al-8Nb-0.2B,Ti-45Al-4Nb-0.5Hf-0.1Y-0.2B,Ti-45Al-7Nb-0.1Hf-0.1Y-0.2B(at%),研究了这3种合金在900℃静止空气中的断续氧化行为。研究结果表明:Hf、Y联合微合金化的合金氧化膜与基体粘附性明显增强;低Nb/Hf比值的Ti-45Al-4Nb-0.5Hf-0.1Y-0.2B合金的氧化增重小、抗氧化性强,高Nb/Hf比值的Ti-45Al-7Nb-0.1Hf-0.1Y-0.2B合金的氧化增重大,抗氧化性差。对氧化膜的扫描电镜(SEM)、能谱(EDS)及X射线衍射(XRD)分析表明,Hf、Y的联合加入促进了Al2O3膜的须状生长形态,从而提高了氧化膜与基体粘附性,低Nb/Hf比值的合金中形成了较厚的连续致密的Al2O3膜,提高了合金的抗氧化性;高Nb/Hf比值的合金内存在明显的外氧化现象,导致了该合金抗氧化性下降。
Ti-45Al-8Nb-0.2B, Ti-45Al-4Nb-0.5Hf-0.1Y-0.2B and Ti-45Al-7Nb-0.1Hf-0.1Y- 0.2B (at%). The intermittent oxidation behavior of these three alloys in still air at 900 ℃ was studied. The results show that the adhesion of Hf and Y microalloyed alloy oxide matrix to the substrate is obviously enhanced; the oxidation weight gain of Ti-45Al-4Nb-0.5Hf-0.1Y-0.2B alloy with low Nb / Hf ratio is small, The Ti-45Al-7Nb-0.1Hf-0.1Y-0.2B alloy with high oxidation resistance and high Nb / Hf ratio has large oxidation weight gain and poor oxidation resistance. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis of the oxide film showed that the combined addition of Hf and Y promoted the morphology of the whisker growth of the Al2O3 film and improved the adhesion of the oxide film to the substrate The formation of a thicker continuous dense Al2O3 film in the alloy with low and high Nb / Hf ratio increased the oxidation resistance of the alloy. The obvious external oxidation occurred in the alloy with high Nb / Hf ratio, which led to the oxidation resistance of the alloy Sexual decline.