Deformation of Ni-Mn-Ga 7M modulated martensite through detwinning/twinning and forward/reverse intermartensitic transformation studied by in-situ neutron diffraction and interrupted in-situ EBSD
Deformation of Ni-Mn-Ga 7M modulated martensite through detwinning/twinning and forward/reverse intermartensitic transformation studied by in-situ neutron diffraction and interrupted in-situ EBSD
复制标题
通过原位中子衍射和间断原位 EBSD 研究 Ni-Mn-Ga 7M 调制马氏体通过解孪生/孪生和正向/反向马氏体相变的变形
DOI：
10.1016/j.actamat.2019.05.054
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发表时间：
2019
期刊：
影响因子：
9.4
通讯作者：
Liang Zuo
中科院分区：
文献类型：
--
作者：
Naifu Zou;Zongbin Li;Yudong Zhang;Weimin Gan;Bo Yang;Xiang Zhao;Claude Esling;Michael Hofmann;Liang Zuo
形状记忆合金，特别是新近发展的Ni-Mn基Heusler型金属间化合物，对机械载荷表现出特殊的力学响应。虽然已经研究了变形行为以减少马氏体变体的数量，但其机制尚未完全揭示。因此，本文采用宏观尺度上的原位中子衍射和微观尺度上的中断原位EBSD研究了Ni-Mn-Ga金属间化合物中孪晶相关的7 M调制马氏体的压缩过程。结果表明，7 M马氏体的力学响应具有三种状态：线性弹塑性状态、稳态塑性状态和第二线性塑性状态。塑性变形是由在第一线性状态下的现有变体的解孪晶开始的。通过这些变体的强烈去孪晶和通过剩余变体的孪晶导致现有变体的消失和新变体的出现，然后通过中间马氏体转变形成非调制马氏体（NM），其进行到稳定状态。这三个剪切过程是高度协调和兼容的本地不相容应变的湮灭逆intermartensitic转变，这使得一个稳定的进展的变形和连续的重新取向的变种。再取向产生新的孪晶，其取向不利且变形能力有限，导致进一步变形的应力增加。本研究提供了Ni-Mn-Ga 7 M马氏体在每个特征变形步骤的变形机制的全面信息，这对于金属间化合物变形行为的力学模拟是有用的。
Shape memory alloys, especially the newly developed Ni–Mn-based heusler-type intermetallic compounds, exhibit specific mechanical responses to mechanical loading. Although the deformation behaviors have been studied for reducing the number of martensite variants, the mechanisms are not fully revealed. Thus in this work the compression process of twin-related 7M modulated martensite of Ni–Mn-Ga intermetallic compound was studied byin-situneutron diffraction at macroscopic scale and by interruptedin-situEBSD at microscopic scale. It is revealed that the mechanical response of the 7M martensite is featured by three states: a linear elastic-plastic state, a steady plastic state, and a second linear plastic state. The plastic deformation is initiated by the detwinning of the existing variants in the first linear state. It proceeds to the steady state by intensive detwinning of the these variants and by twinning of the remaining variants that result in the disappearance of the existing variants and the appearance of new variants, then by intermartensitic transformation to form non-modulated martensite (NM). These three shear processes are highly coordinated and compatible with the annihilation of the local incompatible strains by reverse intermartensitic transformation, which allows a steady progress of deformation and a continuous reorientation of the variants. The reorientation produces new twins with unfavorable orientations and limited deformation capacity, leading to a stress increase for further deformation. The present work provides comprehensive information on deformation mechanisms of Ni–Mn-Ga 7M martensite at each characteristic deformation step that is useful for mechanical simulation of deformation behaviors of intermetallic compounds.