中文摘要：

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。

英文摘要：

The influence of Y addition on cyclic oxidation behaviors of Ti45Al8Nb alloys（at%） was investigated in air at 900℃ by SEM,XRD and EDS.Results show that proper Y addition can markedly increase cyclic oxidation resistance of the alloys.The grain sizes are gradually decreased with the increasing Y content.In cyclic oxidation tests all Y added alloys except Ti45Al8Nb0.1Y show no obvious scale spallation after 1000 cycles while Y free alloy shows serious spallation even after 300 cycles.Y addition enhances the adhesion between the oxide film and the substrate.However,alloys with excessive Y suffer severe internal oxidation by providing rapid diffusion paths for O in the form of coarse Y2O3 particles at oxide grain boundary.