First‐Principles Characterization of Equilibrium Vacancy Concentration in Metamagnetic Shape Memory Alloys: An Example of Ni2MnGa
First‐Principles Characterization of Equilibrium Vacancy Concentration in Metamagnetic Shape Memory Alloys: An Example of Ni2MnGa
复制标题
变磁形状记忆合金中平衡空位浓度的第一性原理表征：以 Ni2MnGa 为例
DOI：
10.1002/pssb.201700523
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
T. Duong
中科院分区：
文献类型：
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作者：
Yuhao Wang;D. Salas;Bharat K. Medasani;P. Entel;I. Karaman;R. Arróyave;T. Duong
尽管有证据表明空位在超磁形状记忆合金（mmsma）的马氏体相变（MT）行为中起着重要作用，但对这些系统中点缺陷的热力学和动力学的理论甚至实验工作却很少。由于mmsma的MT行为对其磁热响应有很大影响，因此研究mmsma中的空位演变具有潜在的重大技术影响。研究的缺乏可能是由于研究空位性质及其对材料性能的影响的表征能力有限。目前的工作旨在将大规范稀溶液模型应用于Ni2MnGa中点缺陷的平衡（热）种群的研究，Ni2MnGa用作原型MMSMA。热力学模型与含缺陷超级单体结构能量学的第一性原理计算相结合。这种表征能力使得考虑了空位自由度的mmsma的研究更加现实，从而开辟了许多有趣的研究课题。本文通过研究空位浓度在Ni2MnGa的有序-无序（ODO）过程动力学和MT温度中的作用，证明了基于第一性原理的表征方法的能力。
Despite the fact that there is evidence for the important role that vacancies play in the martensitic transformation (MT) behavior of metamagnetic shape memory alloys (MMSMAs), little theoretical – and even experimental – work on the thermodynamics and kinetics of point defects in these systems has been carried out. Since the MT behavior of MMSMAs has a great influence on their magneto‐caloric response, investigating the vacancy evolution in MMSMAs has potentially a significant technological impact. Scarcity of studies may be due to the limited characterization capability available for studying vacancy properties as well as their impacts on the materials performance. The current work seeks to introduce the application of the grand‐canonical dilute‐solution model to the investigation of equilibrium (thermal) populations of point defects in Ni2MnGa, used as a prototypical MMSMA. The thermodynamic model is coupled to first‐principles calculations of the energetics of defect‐containing supercell structures. Such characterization capability allows for more realistic investigations of MMSMAs with the vacancy degree of freedom taken into account and subsequently opens up many interesting research topics. Here we demonstrate the capability of the first principles based characterization method by investigating the role of vacancy concentration in the kinetics of order–disorder (ODO) process and the MT temperature of Ni2MnGa.