摘要:
运用基于密度泛函理论的第一性原理的投影缀加波方法,对Hg2CuTi型Mn2NiAl在由立方结构至四方结构的畸变过程中电子结构和磁性的变化规律及其对压力响应的规律进行了研究.研究发现：在由奥氏体相到马氏体相的相变中,由于Ni-Mn（A）原子间距的减小而使得杂化程度增强,导致占据态的态密度向低能区域移动,体系的能量降低,致使在马氏体相中的稳定性增大;在从奥氏体相到马氏体相的相变中,能带变宽,成键作用加强,从而在马氏体相中的稳定性增大;在四方畸变过程中,总磁矩的变化主要来源于Ni原子磁矩的变化;计算得到Mn2NiAl的零压体积弹性模量为125.69GPa,其抗压缩性比其他常见的Heusler型合金弱.
Abstract:
The change rules of electronic structure and magnetism in the process of transform from a cubic structure to a tetragonal structure and their responses to pressure for Hg2CuTi-type Mn2NiAl are studied by first principles method based on the density functional theory.The study shows that in the process of transform from a cubic austenite phase to a tetragonal martensite phase,the shift of the density of states of occupied state to ward lower energy in the martensitic phase results from the enhanced Ni-Mn（A） hybridization caused by a decrease in the Ni-Mn（A） distance,and it is the reason for the stabilization of the martensitic phase.In the process of transform from the austenite phase to the martensite phase,the bonding interaction becomes stronger,owing to energy band broadening,and it can improve the stabilization in the martensitic phase.In the process of tetragonal distortions,the change of total magnetic moment is determined by the change of magnetic moment of Ni atom.The bulk modulus at zero pressure of Mn2NiAl is calculated to be 125.69 GPa,so that we expect Mn2NiAl to be the more compressible material than the familiar Heusler alloys.
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