Large field induced strain in single crystalline Ni–Mn–Ga ferromagnetic shape memory alloy
Large field induced strain in single crystalline Ni–Mn–Ga ferromagnetic shape memory alloy
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DOI：
10.1063/1.372518
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发表时间：
2000-04
影响因子：
3.2
通讯作者：
S. J. Murray;M. Marioni;A. M. Kukla;J. Robinson;R. O'handley;S. Allen
中科院分区：
文献类型：
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作者：
S. J. Murray;M. Marioni;A. M. Kukla;J. Robinson;R. O'handley;S. Allen
在具有接近于Heusler合金Ni 2 MnGa的组成的Ni-Mn-Ga单晶中报道了5.7%的室温自由剪切应变。在2 mm×2 mm×25 mm的单晶中，用表面场强为320000 A/m的永磁体产生孪晶界。在孪晶界处，样品中出现6.5°的急剧弯曲。表面磁化强度在这个边界上突然变化。通过相对于磁体边缘移动样品，我们能够沿着晶体长度沿着来回扫描边界。使用霍尔探针测量了表面磁化强度，结果证实了易磁化轴是四磁化轴。粉末x-射线衍射表明，该材料的fcc到体心四轴bct马氏体转变涉及bct单元c/a比从1.33到约1.33降低6%。因此，最大可实现应变估计为6.2%。系统中的孪晶面是{112}bct，并被观察到几乎垂直于长轴。
A room temperature free shear strain of 5.7% is reported in a single crystal of Ni–Mn–Ga having a composition close to the Heusler alloy Ni2MnGa. A twin boundary was created in a 2 mm×2 mm×25 mm single crystal using a permanent magnet with surface field strength of about 320 000 A/m. A sharp 6.5° bend occurs in the sample at the twin boundary. The surface magnetization changes abruptly across this boundary. By moving the sample relative to the edge of the magnet, we were able to sweep the boundary back and forth along the crystal length. Surface magnetization was measured using a Hall probe and the results confirm that the easy axis is the tetragonal c axis. Powder x-ray diffraction shows that the fcc to body-centered-tetragonal bct martensitic transition of this material involved a 6% reduction of the bct cell c/a ratio, from √ to about 1.33. The maximum achievable strain is thus estimated to be 6.2%. The twin planes in the system are the {112}bct and were observed to lie almost normal to the long axis o...