Ni-Mn-Ga-Cu铁磁形状记忆合金的晶体结构、相稳定性和磁性能的第一性原理研究

发布时间：2018-07-21 22:09

【摘要】：采用第一原理计算方法系统地研究了Cu含量对Ni-Mn-Ga-Cu铁磁形状记忆合金的晶体结构、相稳定性和磁性能的影响。形成能的计算结果表明,在Ni2MnGa合金中,添加的第四组元Cu将优先占据Mn的亚晶格格点,从而为实验中的成分设计提供了理论依据。随着Cu含量的增加,铁磁性奥氏体的相稳定性逐渐减弱,而顺磁性奥氏体的相稳定性则逐渐增强,导致顺磁性奥氏体和铁磁性奥氏体的基态总能量之间的差值减小,这是此类合金Curie温度TC随Cu含量的增加而降低的本质原因。而实验上观察到的马氏体相变温度Tm随合金元素Cu含量的增加而升高的现象本质上是由于奥氏体与马氏体两相之间的能量差增大,从而提高了马氏体相变的驱动力所致。此外,Ni-Mn-Ga-Cu合金的磁性能随Cu含量的增加而减弱,并从电子态密度的角度阐释了磁性能降低的原因。
[Abstract]:The effect of Cu content on the crystal structure, phase stability and magnetic properties of Ni-Mn-Ga-Cu ferromagnetic shape memory alloy was systematically studied by the first principle calculation method. The calculation results of formation energy show that the addition of the fourth component Cu will preferentially occupy the subcrystalline lattice of mn in Ni _ 2MnGa alloy, which provides a theoretical basis for the composition design in the experiment. With the increase of Cu content, the phase stability of ferromagnetic austenite decreases gradually, while the phase stability of paramagnetic austenite increases gradually, which results in the decrease of the difference between the total energy of the ground state of paramagnetic austenite and ferromagnetic austenite. This is the essential reason for the decrease of Curie temperature TC with the increase of Cu content. However, the phenomenon that the martensite transformation temperature TM increases with the increase of Cu content is essentially due to the increase of the energy difference between austenite and martensite, which increases the driving force of martensite transformation. In addition, the magnetic properties of Ni-Mn-Ga-Cu alloys decrease with the increase of Cu content, and the reasons for the decrease of magnetic properties are explained from the point of view of electronic density of states.
【作者单位】：东北大学材料各向异性与织构教育部重点实验室;东北大学秦皇岛分校资源与材料学院;河北省电介质与电解质功能材料实验室;
【基金】：国家自然科学基金项目Nos.51301036和51431005 国家高技术研究发展计划项目No.2015AA034101 中央高校基本科研业务费专项资金项目No.N130523001 河北省自然科学基金项目No.E2013501089资助~~
【分类号】：TG139.6

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