Mechanical properties and microstructural stability under the service temperature are important to the high temperature titanium alloy.In order to evaluate the potential in increase the service temperature of Ti alloy,two near-α Ti alloys with high content of Al as α-stabilizer and Ta,Nb and/or Re as β-stabilizers were designed and prepared by ingot metallurgy and thermomechanical processing,and the microstruc-ture and mechanical properties before and after thermal exposure at 650℃for 100 h were character-ized.The results indicated that due to the weak β-stabilizing ability of Ta and Nb elements,only a small amount of β phase was formed in Ti-10Al-4Ta-2Nb alloy.With a trace Re addition,the β phase was obviously increased in Ti-10Al-4Ta-2Nb-0.25Re,indicating that the Re was a strong β-stabilizer.Under the same thermomechanical conditions,the Re addition decreased the volume fraction of primary α(αp)phase and refined the secondary α(αs)phase evidently.The primary α phase presented an obvious core-shell structure in the Ti-10Al-4Ta-2Nb alloy,with higher Al concentration in the shell.While the core-shell structure was not obvious in the Re-containing alloy due to the Re decreases the diffusion of Al,Ta and Nb elements.A large number of ordered α2 precipitates can be observed in the αp and αs phases of two alloys.The α2 precipitates continuously grew up during thermal exposure,however,their growth rate in the αs phase of Re-containing alloy were lower than that of Ti-10Al-4Ta-2Nb alloy.Al-though plenty of ordered α2 precipitates formed in the Ti-10Al-4Ta-2Nb alloy,the alloy had a certain plasticity at room temperature.The trace Re addition evidently increased the tensile strength but caused the decrease of the plasticity.After thermal exposure,the strength was further increased,while the plas-ticity was decreased for both of alloys.

Juan Li;Yaqun Xu;Wenlong Xiao;Chaoli Ma;Xu Huang

Key Laboratory of Aerospace Advanced Materials and Performance of Ministry of Education,School of Materials Science and Engineering Beihang University,Beijing 100191,China;AECC Beijing Institute Of Aeronautical Materials,Beijing 100095,China

材料科学技术（英文版）

[1]Juan Li;Yaqun Xu;Wenlong Xiao;Chaoli Ma;Xu Huang-.Development of Ti-Al-Ta-Nb-(Re)near-α high temperature titanium alloy:Microstructure,thermal stability and mechanical properties)[J].材料科学技术（英文版）,2022(14):1-11

4Ta,25Re

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