Cr和W对TiAl-Nb合金微观组织与力学性能的影响

    Effects of Cr and W on Microstructure and Mechanical Properties of TiAl-Nb Alloys

    • 摘要: 采用真空电弧非自耗熔炼方法制备了Ti-Al-Nb-xCr-yW-Si(x=1.5、2.5、3.5,y=0.5、1.0、2.0,原子分数,%,下同)合金,研究了随Cr,W元素含量变化,该合金的微观组织与室温/高温的抗压缩力学性能。结果表明:铸态合金的微观组织中主要由片层组织(α2+γ)和γ/B2相组成,随Cr、W元素含量增加,B2相增多,片层组织减少,当Cr、W元素增加至3.5%、2.0%时,合金中出现了粗大的类似羽毛状的组织,Cr元素的β稳定能力要强于W元素。随着Cr元素含量的增加,合金压缩的峰值应力逐渐降低;而随着W元素含量的增加,合金压缩的峰值应力逐渐增加,其中Ti-44Al-5Nb-2.5Cr-1.5W-0.5Si合金具有最高的峰值应力和延展性。

       

      Abstract: Ti-Al-Nb-xCr-yW-Si (x=1.5, 2.5, 3.5, y=0.5, 1.0, 2.0, at%)alloys were prepared by vacuum arc melting.The microstructure and compressive mechanical properties of alloys with the change of Cr and W contents were studied.The results show that the microstructure of as-cast alloys is mainly composed of lamellar structure (α2+γ)and B2 phase.With the increase of Cr and W contents, B2 phase increases and lamellar structure decreases.When Cr and W increase to 3.5% and 2.0%, coarse feather like structure appears in alloys.β phase stability of Cr is stronger than that of W element.The peak stress of the alloy in compression decreases with the increase of Cr content, while the peak stress of alloy in compression increases with the increase of W content, and Ti-44Al-5Nb-2.5Cr-1.5W-0.5Si alloy shows the highest peak stress and ductility.

       

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