【摘 要】
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The microstructural evolution,oxidation resistance and mechanical properties of Ti-6.5Al-2Sn-4Hf-2Nb-based alloys with different contents of tungsten (W) additions ranging from 0 to 4.0 wt.％ have been investigated in this study.The addition of W changed t
【机 构】
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Key Laboratory of Aerospace Advanced Materials and Performance of Ministry of Education,School of Ma
论文部分内容阅读
The microstructural evolution,oxidation resistance and mechanical properties of Ti-6.5Al-2Sn-4Hf-2Nb-based alloys with different contents of tungsten (W) additions ranging from 0 to 4.0 wt.％ have been investigated in this study.The addition of W changed the microstructure from Widmanst(a)tten colony of the W-free alloy to basketweave microstructure.After thermal exposure at 650 ℃ for 1000 h,the retained β phase became less continuous,and secondary β nano-particles with high W concentration were pre-cipitated from α lamellas.Within α lamellas,the W was found to mainly partitioned into the secondary β phase and refined the ordered α2-Ti3Al precipitates due to increased solubility of Nb in α2 phase.High W addition increased activation energy for oxidation,promoting the formation of more uniform and com-pact compound oxides,therefore substantially enhanced the oxidation resistance of the alloy.Besides,the W addition also improved the room and high-temperature yield strength without obviously losing plas-ticity after long-time thermal exposure.The improved mechanical performance was mainly attributed to the introduction of more α/β interfaces,the precipitation of secondary β phase and the refined α2 phase with Nb segregation.
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