Ti-Nb ( < 24) shape memory alloys (SMAs) typically exhibit triangular self-accommodation morphology of α” martensite after thermal β→α” transformation, whereas α” variants contain no internal twins. In present work, we found an interesting transition from the self-accommodated triangular into nano-twinned martensite morphology during tensile deformation in solution treated Ti-20Nb-(3, 6)Zr SMAs. Such transition was not observed in binary Ti-20Nb. Moreover, the superelasticity in the deformed Ti-20Nb-(3, 6)Zr SMAs is greatly improved by several times as compared to that in Ti-20Nb. The underlying mechanisms of superelasticity and its improvement are briefly discussed based on the phenomenological models concerning the self-accommodation morphology transition.

中文翻译：

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Ti-Nb-Zr形状记忆合金中变形诱导从三角形马氏体到纳米孪晶马氏体的自调节形貌转变

Ti-Nb (< 24) 形状记忆合金 (SMA) 在热 β→α” 转变后通常表现出 α” 马氏体的三角形自调节形态，而 α” 变体不包含内部孪晶。在目前的工作中，我们发现在固溶处理的 Ti-20Nb-(3, 6)Zr SMA 拉伸变形过程中，从自调节三角形到纳米孪晶马氏体形态的有趣转变。在二元 Ti-20Nb 中没有观察到这种转变。此外，变形后的Ti-20Nb-(3, 6)Zr SMA的超弹性较Ti-20Nb大大提高了数倍。基于自调节形态转变的现象学模型，简要讨论了超弹性的潜在机制及其改进。