Unprecedented non-hysteretic superelasticity of [001]-oriented NiCoFeGa single crystals
Unprecedented non-hysteretic superelasticity of [001]-oriented NiCoFeGa single crystals
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DOI：
10.1038/s41563-020-0645-4
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发表时间：
2020-03-16
期刊：
影响因子：
41.2
通讯作者：
Ren, Yang
中科院分区：
文献类型：
--
作者：
Chen, Haiyang;Wang, Yan-Dong;Ren, Yang
与马氏体相变相关的超弹性已经发现了广泛的工程应用（1，2）。然而，一阶相变的固有滞后（3）和温度敏感性（4）显著阻碍了智能金属元件在许多关键领域的使用。在这里，我们报告了一个大的超弹性高达15.2%的应变在[001]取向的NiCoFeGa单晶，表现出非滞后的机械响应，一个小的温度依赖性和高能量存储能力和循环稳定性在很宽的温度和组成范围。原位同步辐射X射线衍射测量表明，超弹性与应力引起的晶格参数的连续变化伴随着结构波动。中子衍射和电子显微镜观察揭示了一种前所未有的微观结构，由有序和无序晶体结构的原子级纠缠组成，可以通过操纵来调节超弹性。NiCoFeGa单晶在很宽的温度和成分范围内表现出很大的非滞后超弹性。这归因于外加应力作用下的连续相变，这与有序和无序晶体结构的纠缠涨落有关。
Superelasticity associated with the martensitic transformation has found a broad range of engineering applications(1,2). However, the intrinsic hysteresis(3) and temperature sensitivity(4) of the first-order phase transformation significantly hinder the usage of smart metallic components in many critical areas. Here, we report a large superelasticity up to 15.2% strain in [001]-oriented NiCoFeGa single crystals, exhibiting non-hysteretic mechanical responses, a small temperature dependence and high-energy-storage capability and cyclic stability over a wide temperature and composition range. In situ synchrotron X-ray diffraction measurements show that the superelasticity is correlated with a stress-induced continuous variation of lattice parameter accompanied by structural fluctuation. Neutron diffraction and electron microscopy observations reveal an unprecedented microstructure consisting of atomic-level entanglement of ordered and disordered crystal structures, which can be manipulated to tune the superelasticity. The discovery of the large elasticity related to the entangled structure paves the way for exploiting elastic strain engineering and development of related functional materials.NiCoFeGa single crystals exhibit large non-hysteretic superelasticity over broad temperature and composition ranges. It is attributed to the continuous phase transition with applied stress, which is related to the fluctuation of entangled ordered and disordered crystal structures.