Nb元素对粉末冶金TiAl基合金高温氧化行为的影响  

Effect of Nb on high temperature oxidation behavior of powder metallurgy TiAl based alloy

作　　者：欧阳思慧 刘彬[1] 李建波[1] 徐礼友[1] 刘咏[1] 

机构地区：[1]中南大学粉末冶金国家重点实验室,长沙410083

出　　处：《粉末冶金材料科学与工程》2015年第4期616-622,共7页Materials Science and Engineering of Powder Metallurgy

基　　金：国家重点基础研究发展规划(973计划)资助项目(2011CB605505)

摘　　要：采用等离子旋转电极法制备Ti-47Al-2Cr-0.2Mo,Ti-50Al-2Nb-0.3W和Ti-45Al-7Nb-0.3W(元素含量均为原子分数,%)3种预合金粉末,再通过热等静压制备成块体合金,在950℃空气环境中进行合金的高温氧化实验,并利用扫描电镜(SEM)观察与分析合金氧化后的表面形貌以及截面的元素面分布,用X射线衍射(XRD)分析氧化膜的相组成,研究Nb元素及其含量对Ti Al基合金高温氧化行为的影响。结果表明:Nb元素的添加可提高粉末冶金Ti Al基合金的抗氧化性能,这3种合金中Ti-45Al-7Nb-0.3W合金的抗氧化性能最好,经过80 h氧化后质量增量仅为2.484 mg/cm2,为不含Nb合金的12.44%,并且氧化膜整体厚度最薄,最厚的地方氧化膜厚度约为8.3μm。该合金表面形成连续致密的Al2O3氧化层,氧化膜从外向内依次为TiO2层/Al2O3层/(Ti,Nb)O2层/富Al和Nb层。The alloys Ti-47Al-2Cr-0.2Mo, Ti-50Al-2Nb-0.3W and Ti-45Al-7Nb-0.3W（at.%）with homogeneous microstrueture have been prepared by plasma rotating electrode processing and then hot isostatic pressed. The oxidation behaviors of three Nb containing alloys oxidized at 950 ℃ in air were systematically investigated by scanning electron microscopy and X-ray diffraction. The results of the experiments indicate that oxidation resistance of three power metallurgy TiAl based alloys is significantly improved by Nb addition. For these three alloys, the oxide film formed on Ti-45Al-7Nb-0.3W alloy is the thinnest, and the thickness is about 8.3 μm. The addition of Nb also decreases the critical AI content to form a chemically uniform dense alumina. This uniform alumina layer impedes the inward diffusion of oxygen and the outward diffusion of metallic elements. The alloy prepared displays better oxidation resistance at high temperature in the air. The film structure of Ti-45Al-7Nb-0.3W from outside toward inside is in order of TiO2 layer/Al2O3 layer/（Ti,Nb）O2 layer/Al, Nb-rich layer.

关 键 词：粉末冶金 TIAL基合金 高温氧化 NB 

分 类 号：TG172.82[金属学及工艺—金属表面处理]