Phase Transformations in Ferromagnetic NiMnGa Shape Memory Films
Phase Transformations in Ferromagnetic NiMnGa Shape Memory Films
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DOI：
10.2320/matertrans1989.41.933
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发表时间：
2000-08
影响因子：
1.2
通讯作者：
M. Wuttig;C. Crăciunescu;J. Li
中科院分区：
文献类型：
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作者：
M. Wuttig;C. Crăciunescu;J. Li
本文介绍了在硅悬臂梁衬底上溅射沉积铁磁NiMnGa薄膜的最新工作。如果衬底在沉积期间保持在室温（RT）下，则膜是部分结晶的。它们在400°C退火后变成完全结晶。RT沉积的内部摩擦（IF）显示出归因于膜的纳米结构的峰。在室温下沉积并退火的膜以及在保持高于385°C的衬底上沉积的膜显示出与NiTi形状记忆膜相当的转变。然而，阻尼低一个数量级。退火不会显著改变在385°C或更高温度下沉积的膜的相变。对名义上为Ni 50 Mn 25 Ga 25薄膜的弹性模量随磁场变化的温度依赖性的测量表明，磁各向异性场与相变应变（c/a - 1）成比例地增加，从50°C时的0.3 T增加到-150 ° C时的0.8 T。
The paper presents recent work on ferromagnetic NiMnGa films sputter deposited on silicon cantilever substrates. The films are partially crystalline if the substrate is held at room temperature (RT) during the deposition. They become fully crystalline after annealing at 400°C. The internal friction (IF) of the RT deposition shows a peak that is attributed to the nanostructure of the film. Films deposited at RT and annealed and films deposited on substrates held above 385°C show a transformation comparable to NiTi shape memory films. However, the damping is one order of magnitude lower. Annealing does not significantly change the phase transformation of films that were deposited at 385°C or above. Measurements of the temperature dependence of the change of the elastic modulus as a function of the magnetic field of a nominally Ni 50 Mn 25 Ga 25 film suggest that the magnetic anisotropy field increases proportional to the transformation strain, (c/a - 1), from 0.3 T at 50°C to 0.8 T at -150°C.