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采用金刚石对顶砧高压装置(DAC)和同步辐射X射线光源法,对Heusler类型的磁性形状记忆合金Mn2NiGa的结构进行了原位高压X射线衍射测量,并对卸载后的受压样品进行了磁测量.实验观察到材料在室温下分别在0.77GPa和20GPa压力下发生了两次不可逆结构相变:马氏体相变和两种不同马氏体间的等结构相变.同时加压使马氏体结构中产生了大量的缺陷,造成了严重的晶格畸变,致使马氏体结构的矫顽力提高了近10倍,达到204kA/m.结果发现,加压处理造成样品马氏体相饱和磁化强度的大幅度降低,显示出明显的缺陷效应.
The structures of Heusler-type magnetic shape memory alloy Mn2NiGa were measured by in-situ high pressure X-ray diffraction (XRD) using a diamond anvil cell (DAC) and synchrotron X-ray source method. The results show that the material undergoes two irreversible structural phase transitions at room temperature of 0.77 GPa and 20 GPa respectively: martensitic transformation and isostructural transformation between two different martensites, A large number of defects were produced in the structure of the austenite, resulting in serious lattice distortion, resulting in the coercivity of the martensite structure being increased by nearly 10 times to 204 kA / m. The results showed that the sample treated by the pressurization treatment had a martensite phase Saturation magnetization greatly reduced, showing obvious defects.