Lüders-like band front motion and fatigue life of pseudoelastic polycrystalline NiTi shape memory alloy

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• 作者：Lin Zheng^a ; Yongjun He^a ; ^{yongjun.he@ensta-paristech.fr" class="auth_mail" title="E-mail the corresponding author} ; Ziad Moumni^a ; ^b
• 关键词：Fatigue ; Shape memory alloys ; Shear bands (localized deformation) ; Martensitic phase transformation ; Superelasticity
• 刊名：Scripta Materialia
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：123
• 期：Complete
• 页码：46-50
• 全文大小：989 K

文摘

We conducted tensile fatigue tests on polycrystalline NiTi strips with in-situ optical observation on the evolution of the localized deformation (Lüders-like band) in order to trace the deformation history of the fatigue-failure material point in the strips under various loadings. It is found that the band front motion triggering localized cyclic phase transformation leads to a short fatigue life while the “elastic” deformation (without the band front motion) results in a much longer life whose failure crack nucleates away from the immobile band front. The results provide hints to derive a material fatigue criterion from the structure fatigue tests.