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以Ti-42Al-8Nb-0.2W-0.1Y(at%)合金为研究对象,通过热处理获得全片层组织,片层团尺寸约为85μm,在900℃空气条件下,对合金进行了100 h的抗氧化实验,主要研究了该Ti Al-Nb合金的高温抗氧化行为,并对氧化层的结构、成分及形成过程进行了深入分析。利用OM、SEM、XPS、XRD、和EDS对试样的微观结构、相组成及微区成分进行表征。结果表明:在900℃空气条件下,具有全片层组织的Ti Al-Nb合金,其恒温氧化动力学曲线符合近抛物线规律;长时氧化后,合金表面生成了结晶状颗粒氧化物,为Ti O2和A12O3的混合物;氧化层主要由外表面氧化层、中间过渡层和基体层构成,氧化膜完整厚度大约为6μm。由此可知,添加了合金元素且具有小尺寸片层团组织的Ti Al合金在900℃高温时,具有较好的抗氧化性能。
The microstructure of Ti-42Al-8Nb-0.2W-0.1Y (at%) alloy was studied by heat treatment. The size of the lamellar layer was about 85μm. The microstructure of the alloy was investigated under air at 900 ℃ for 100 h , The oxidation behavior of the TiAl-Nb alloy was studied at high temperature, and the structure, composition and formation process of the oxide layer were analyzed in depth. The microstructure, phase composition and micro-zone composition of the samples were characterized by OM, SEM, XPS, XRD and EDS. The results show that at constant temperature of 900 ℃, TiAl-Nb alloy with full lamellar microstructure exhibits a constant parabolic curve. The long-term oxidation results in the formation of crystalline particulate oxides on the surface of TiAl-Nb alloy. O2 and A12O3 mixture; the oxide layer is mainly composed of the outer surface oxide layer, the intermediate transition layer and the base layer, the complete thickness of the oxide film is about 6μm. It can be seen that the TiAl alloy with alloying elements and small size lamellar structure has good oxidation resistance at 900 ℃.