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利用SEM、XRD和EDS研究Y对Ti45Al8Nb(at%)合金在900℃空气中的循环氧化行为的影响。实验结果表明,适量Y的加入显著提高了合金的抗循环氧化性。无Y合金300次循环后便出现了表层氧化膜脱落,而含Y的6个合金除Ti45Al8Nb0.1Y在氧化460h后出现大面积脱落外,其余合金在1000次循环内均未出现明显脱落。Y的加入显著增强了氧化膜与基体之间的粘附性。但是加入过量Y,合金氧化膜内颗粒较大的Y2O3偏聚在晶界处,为O提供了扩散通道,使合金出现了严重的内氧化。
The effects of Y on the cyclic oxidation of Ti45Al8Nb (at%) alloy in air at 900 ℃ were investigated by SEM, XRD and EDS. The experimental results show that the addition of proper amount of Y significantly improves the cyclic oxidation resistance of the alloy. After 300 cycles without Y alloy, the oxide film on the surface appeared to fall off. However, all the 6 alloys containing Y except Ti45Al8Nb0.1Y showed a large area peeled off after 460 h of oxidation, and the other alloys did not show any obvious drop off within 1000 cycles. The addition of Y significantly enhances the adhesion between the oxide film and the substrate. However, the addition of excessive Y, Y2O3 in the oxide film of the alloy segregates at the grain boundaries and provides diffusion channels for O, resulting in serious internal oxidation of the alloy.