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研究了β相凝固的铸造合金Ti45Al8Nb0.2W0.25Cr和Ti45Al8Nb0.2W0.25Cr0.2B0.02Y合金900℃×130 h的循环抗氧化性能,探讨了B、Y元素对合金抗氧化性能的影响。结果表明,0.2B0.02Y的添加能在一定程度上改善合金的抗氧化性能。B、Y的加入能够促进合金表层形成致密连续的Al2O3层,抑制氧元素的进一步入侵,Y的加入使得合金氧化层的抗剥落性能得到提高。分析计算得出了两种合金的氧化动力学曲线,氧化10 h后,Ti45Al8Nb0.2W0.25Cr合金的氧化动力学方程中的幂指数n=1.87,合金单位面积的氧化增重随氧化时间的变化规律介于直线规律和抛物线规律之间,即这种合金的氧化膜保护性不足。Ti45Al8Nb0.2W0.25Cr0.2B0.02Y合金氧化动力学方程中的幂指数n=2,合金单位面积的氧化增重随氧化时间的变化规律为抛物线规律,利于合金表面生成保护性的氧化膜,合金的抗氧化性较好。
The cyclic oxidation resistance of β-phase solidified alloy Ti45Al8Nb0.2W0.25Cr and Ti45Al8Nb0.2W0.25Cr0.2B0.02Y was investigated at 900 ℃ for 130 h. The effects of B and Y on the oxidation resistance of the alloy were also investigated. The results show that the addition of 0.2B0.02Y can improve the oxidation resistance of the alloy to a certain extent. The addition of B and Y can promote the formation of dense and continuous Al2O3 layer on the surface of the alloy and inhibit the further invasion of oxygen. The addition of Y makes the oxidation resistance of the alloy oxide layer better. The oxidation kinetics curves of the two alloys were obtained by analysis and calculation. The oxidation exponent n = 1.87 in the oxidation kinetics equation of Ti45Al8Nb0.2W0.25Cr alloy after oxidation for 10 h, the oxidation weight gain per unit area changed with the oxidation time The law is between the linear law and the parabolic law, that is, the oxide film of this alloy is not sufficiently protective. The power exponent n = 2 in the oxidation kinetics equation for Ti45Al8Nb0.2W0.25Cr0.2B0.02Y alloy shows a parabolic law with respect to oxidation time, which is conducive to the formation of a protective oxide film on the alloy surface. The alloy Good oxidation resistance.