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Cryogenic tensile properties and deformation behavior of a superhigh strength metastable beta titanium alloy Ti–15Mo–2Al
Materials Science and Engineering: A ( IF 6.4 ) Pub Date : 2021-05-05 , DOI: 10.1016/j.msea.2021.141344
M.C. Zang , H.Z. Niu , H.R. Zhang , H. Tan , D.L. Zhang

Considering the great potential of extremely-low temperature applications, cryogenic tensile properties and deformation behavior of a metastable β-Ti alloy Ti–15Mo–2Al were investigated. Superhigh ultimate tensile strength (UTS) of 1535 MPa at 77 K and 1725 MPa at 20 K are achieved. The elongation-to-fracture (EI) of the alloy is found to be maintained at a high level up to 22.0% at 77 K, but sharply drops down to 4.5% at 20 K. Because of the dynamic Hall-Patch effect induced by the extensive {332}<113> twins formed during deformation and the strong back-stress strengthening at twin boundaries, the work hardening rate and tensile strength are significantly enhanced at 77 K. In contrast to the stable deformation at 298 K and 77 K, a serrated deformation (i.e. discontinuous plastic flow) takes place at 20 K. The related cryogenic deformation mechanism and fracture behavior are illustrated from the dynamics of dislocation pileups and thermophysical activation aspect. It is proposed that cryogenic applications of the metastable β-Ti alloy are practically feasible at least at temperatures not lower than 77 K.



中文翻译:

超高强度亚稳态β钛合金Ti–15Mo–2Al的低温拉伸性能和变形行为

考虑到极低温应用的巨大潜力,对亚稳态β-Ti合金Ti-15Mo-2Al的低温拉伸性能和变形行为进行了研究。在77 K时达到1535 MPa的超高极限拉伸强度(UTS)在20 K时达到1725 MPa的超高极限拉伸强度。断裂伸长率(EI)的合金被发现可以在77 K时保持较高水平,最高可达22.0%,而在20 K时则急剧下降至4.5%。由于广泛的{332} <113>引起的动态霍尔效应效应在变形过程中形成了孪晶,并且在孪晶边界处形成了强大的背应力,在77 K时,工作硬化速率和拉伸强度得到了显着提高。与298 K和77 K时的稳定形变相反,是锯齿形变形(即不连续的塑性流动) )发生在20 K.从位错堆积的动力学和热物理活化方面说明了相关的低温变形机理和断裂行为。提出至少在不低于77 K的温度下亚稳态β-Ti合金的低温应用是切实可行的。

更新日期:2021-05-08
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