Effects of texture on the functional and structural fatigue of a NiTi shape memory alloy

Deformation characterization of low-symmetry phases such as martensite in SMAs is challenging due to a fine-scale hierarchical microstructure. Using X-ray microLaue diffraction, in-situ deformation of martensite is examined in a notched NiTi specimen. The local deformation is influenced by the notch stress field, initial martensite microstructure, and interaction between notch stress field and the external load. The microstructure evolves heterogeneously and inelastically, with detwinning and twin nucleation occurring simultaneously through loading. These results contrast with the traditional view of martensite deformation that is partitioned in three distinct regimes: elasticity, reorientation and de-twinning.

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Yuri I. Chumlyakov

Papers

In-situ, microscale characterization of heterogeneous deformation around notch in martensitic Shape Memory Alloy