Ti-22Al-25Nb合金在B2单相区的热变形行为
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摘要
采用热模拟压缩实验研究了Ti-22Al-25Nb合金在B2单相区的热变形行为。结果表明:与其他温度较低的相区变形行为的对比发现,合金在B2单相区变形时具有更低的流动应力和更弱的流动软化效应。在应力-应变曲线上出现了明显的不连续屈服现象,应变速率越大,不连续屈服现象越显著,但该现象对变形温度变化不敏感。在Zener-Hollomon参数与流动应力σ之间的三种关系中,幂指数型最适合用于描述Ti_2AlNb基合金在B2单相区的热变形过程。计算得到的Ti-22Al-25Nb合金在B2单相区热变形的表观激活能为447.75 kJ/mol。利用Zener-Hollomon参数建立了幂指数型的Ti_2AlNb基合金在B2单相区变形的本构关系。
The hot deformation behavior of Ti-22 Al-25 Nb alloy in B2 single phase region was studied by thermal simulation compression test. The results show that comparing with the deformation behavior at lower temperatures, the deformation in B2 phase region leads to lower flow stress and lower flow softening effect. The obvious discontinous yielding phenomenon occurs at stress-strain curves. The higher the strain rate, the more obvious the discontinuous yielding phenomenon, but the phenomenon is not senstive to the change of deformation temperature. Among the three relationships between the Zener-Hollomon parameter and the flowing stress, the power type relation is most favorable to describe the hot deformation of Ti-22 Al-25 Nb alloy in B2 phase region. The calculated apparent activation energe of the hot deformation of Ti-22 Al-25 Nb alloy in B2 single phase region is 447.75 kJ/mol. The constitutive relation of hot deformation of Ti-22 Al-25 Nb alloy in B2 single phase region is built with power type relation.
The hot deformation behavior of Ti-22 Al-25 Nb alloy in B2 single phase region was studied by thermal simulation compression test. The results show that comparing with the deformation behavior at lower temperatures, the deformation in B2 phase region leads to lower flow stress and lower flow softening effect. The obvious discontinous yielding phenomenon occurs at stress-strain curves. The higher the strain rate, the more obvious the discontinuous yielding phenomenon, but the phenomenon is not senstive to the change of deformation temperature. Among the three relationships between the Zener-Hollomon parameter and the flowing stress, the power type relation is most favorable to describe the hot deformation of Ti-22 Al-25 Nb alloy in B2 phase region. The calculated apparent activation energe of the hot deformation of Ti-22 Al-25 Nb alloy in B2 single phase region is 447.75 kJ/mol. The constitutive relation of hot deformation of Ti-22 Al-25 Nb alloy in B2 single phase region is built with power type relation.
引文
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[3]Chen W,Li J W,Xu L,et al.Development of Ti2AlNb alloys:opportunities and challenges[J].Advanced Materials&Processes,2014,172(2):23-27.
[4]徐斌,曾卫东,何德华,等.Ti-22Al-25Nb合金热变形行为研究[J].热加工工艺,2007,36(1):1-4.
[5]Jia J,Zhang K,Liu L,et al.Hot deformation behavior and processing map of a powder metallurgy Ti-22Al-25Nb alloy[J].Journal of Alloys and Compounds,2014,600:215-221.
[6]Ma X,Zeng W,Xu B,et al.Characterization of the hot deformation behavior of a Ti-22Al-25Nb alloy using processing maps based on the Murty criterion[J].Intermetallics,2012,20(1):1-7.
[7]Sellars C M,M ctegart W J.On the mechanism of hot deformation[J].Acta Metallurgica,1966,14(9):1136-1138.
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[9]Quan G,Wu D,Luo G,et al.Dynamic recrystallization kinetics inαphase of as-cast Ti-6Al-2Zr-1Mo-1V alloy during compression at different temperatures and strain rates[J].Materials Science&Engineering A,2014,589:23-33.
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