Fabrication and characterization of a Ni–Mn–Ga uniaxially textured freestanding film deposited by DC magnetron sputtering
Fabrication and characterization of a Ni–Mn–Ga uniaxially textured freestanding film deposited by DC magnetron sputtering
复制标题
DOI：
10.1016/j.jallcom.2009.09.096
复制
发表时间：
2010-01
影响因子：
6.2
通讯作者：
J. Tillier;D. Bourgault;B. Barbara;S. Pairis;L. Porcar;P. Chometon;D. Dufeu;N. Caillault;L. Carbone
中科院分区：
文献类型：
--
作者：
J. Tillier;D. Bourgault;B. Barbara;S. Pairis;L. Porcar;P. Chometon;D. Dufeu;N. Caillault;L. Carbone
采用直流磁控溅射技术，利用牺牲层获得了均匀的自支撑薄膜。经退火后，薄膜晶化，沿(022)方向有较强的离面织构。退火后薄膜的化学计量比接近目标成分，并在255K左右发生马氏体相变。退火后的薄膜表现出铁磁性，居里温度约为362K。研究了这两种状态和马氏体相变过程中的磁化过程。在1-5T范围内，用饱和逼近定律对实验数据进行了拟合，得到了饱和磁化强度。结果表明，马氏体相的饱和磁化强度比奥氏体相的饱和磁化强度高10%左右。提出了一种基于每种状态的本征磁性的模型，该模型允许描述这种多晶薄膜在马氏体相变过程中的磁化强度M=f(H，T)。利用该模型可以确定奥氏体相中马氏体的质量分数。利用扫描电子显微镜和光学显微镜对材料的形状记忆效应进行了分析，并对材料的电阻温度特性进行了原位测量。
Homogeneous freestanding films have been obtained by the direct current (DC) magnetron sputtering technique using a sacrificial layer. After annealing, the films are crystallized with a strong out-of-plane texture along the (022) direction. The stoichiometry of the annealed films is close to the target composition and leads to a martensitic transformation around 255K. The annealed films demonstrate ferromagnetic behavior with a Curie temperature of about 362K. The magnetization process has been studied on the both states and during the martensitic transition. The saturation magnetizations have been determined by fitting the experimental data with a saturation approach law in the range of 1–5T. Results show the saturation magnetization of the martensite is around 10% higher than that of the austenite. A model based on intrinsic magnetic properties of each state allowing the description of the magnetization M=f(H, T) of such polycrystalline films during the martensitic transformation is presented. The mass fraction of martensite inside the austenite phase can be determined using this model. The shape memory effect is analyzed both by scanning electron microscopy and by optical microscopy with in situ measurement of the resistance temperature dependence.