Co对Ti45Al-8Nb-0.3Y合金组织结构和高温抗氧化性能的影响EI北大核心CSCD

采用真空电弧非自耗熔炼方法制备Ti45Al-8Nb-0.3Y-m Co(m=0,0.5,1,2,原子分数/%,下同)合金,研究合金的组织和高温抗氧化性能。结果表明:Co能够明显细化TiAl-Nb合金组织,但对合金中α_(2)+γ片层组织的形成具有较强烈的抑制作用,并且会促进富Co的B_(2)相析出。Ti45Al-8Nb-0.3Y-mCo合金在1000℃空气中氧化100 h后形成的氧化膜均主要由较为疏松的TiO_(2)和Al_(2)O_(3)混合组成,且TiAl-Nb-0.3Y合金的氧化增重随Co含量增加而增大,但氧化膜的抗剥落能力随Co含量增加而明显提高;添加Co能够在一定程度上降低氧化膜的内应力,对提高其抗剥落性能有益,但引起的粗大B_(2)相析出削弱了合金的高温抗氧化性能。

Effect of Co on microstructure and high temperature oxidation resistance of Ti45Al-8Nb-0.3Y alloy

Ti45Al-8Nb-0.3Y-m Co(m=0,0.5,1,2,atom fraction/%)alloys were prepared by vacuum arc non-consumable melting method.The microstructure and high temperature oxidation resistance of the alloys were investigated.The results show that the microstructure of TiAl-Nb alloy can be significantly refined by addition of Co element.However,Co can remarkably inhibit the formation of α₂+γlamellar while promote the formation of Co-rich B₂ precipitations in the alloys.The oxide films formed on the Ti45Al-8Nb-0.3Y-m Co alloys mainly consist of relatively loose TiO₂ and Al₂O₃ mixtures,after oxidation at 1000℃for 100 h in air.With the increase of Co content,the mass gains of the TiAl-Nb-0.3Y alloys after oxidation increase obviously,while much better anti-spalling performance of the oxide films can be obtained.Addition of Co can reduce the internal stress of the oxide film to a certain extent,which is beneficial to the anti-spalling performance of the oxide film.However,the coarse B₂ precipitation caused by Co weakens high temperature oxidation resistance of the alloy.