Ab-initio revelation on the origins of Ti substitution for Ga, Mn and Ni on ferromagnetism, phase stability and elastic properties in Ni2MnGa
Ab-initio revelation on the origins of Ti substitution for Ga, Mn and Ni on ferromagnetism, phase stability and elastic properties in Ni2MnGa
复制标题
从头开始揭示 Ti 取代 Ga、Mn 和 Ni 对 Ni2MnGa 铁磁性、相稳定性和弹性性能的影响
DOI：
10.1016/j.jallcom.2019.153481
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发表时间：
2020
影响因子：
6.2
通讯作者：
Zuo Liang
中科院分区：
文献类型：
--
作者：
Yan Hai-Le;Zhao Ying;Liu Hao-Xuan;Zhang Mei-Juan;Zhang Hai-Feng;Bai Jing;Jia Nan;Yang Bo;Li Zong-Bin;Zhang Yu-Dong;Esling Claude;Zhao Xiang;Zuo Liang
本文用第一性原理计算方法研究了钛替代Ga、Mn和Ni对Ni2MnGa合金的铁磁性、相稳定性、弹性性质和电子结构的影响及其机理。用钛取代镓或锰时，钛倾向于直接取镓或锰位。然而，当钛取代镍时，钛喜欢占据镍中心的锰原子的位置。当钛取代镓时，磁性对钛含量不敏感。相反，当钛取代了锰和镍时，合金的磁化强度和居里温度都大大降低，这分别是由于锰含量的减少和钛的间接占据方式造成的。在晶格稳定性方面，钛替代Ga或Mn(Ni)分别降低或提高了奥氏体相的稳定性。此外，用钛替代Ga是一种有效的马氏体区分异相策略。在弹性性能方面，我们发现用钛取代Ga可以降低合金的本征脆性，这是由于Ni-Ga之间的p-d杂化减少所致。相比之下，用钛替代Ni对合金的塑性不利，但由于Ni-Ga和Mn-Ga之间的p键共存，以及Ni-Ti和Mn-Ti之间的p键共存，可以大大提高合金的本征强度。
In the present work, the effects and the underlying mechanisms of Ti substitution for Ga, Mn and Ni on ferromagnetism, phase stability, elastic properties and electronic structures in Ni2MnGa alloy were studied by first-principles calculations. Upon substitution for Ga or Mn, the Ti prefers to directly take the Ga or Mn sites. However, when Ti replaces Ni, the Ti likes to take the site of Mn atom that occupies the Ni site. When Ti replaces Ga, the magnetism is insensitive to the Ti content. On the contrary, when Ti replaces Mn and Ni, both the magnetization and Curie temperature of the alloy are greatly reduced, which are resulted from the reduced Mn content and the indirect occupation manner of Ti, respectively. For the lattice stability, Ti replacement for Ga or Mn (Ni) reduces or enhances the stability of austenite, respectively. Additionally, Ti substitution for Ga could be an effective strategy to tailorc/aratio of the martensite. As for the elastic properties, we find that Ti substitution for Ga can reduce the intrinsic brittleness of the alloy owing to the decreasedp-dhybridization between Ni–Ga. By contrast, the Ti replacement for Ni is harmful to ductility, but can greatly enhance the intrinsic strength of the alloy owing to the coexistence of thep-dbonds between Ni–Ga and Mn–Ga, and thed-dbonds between Ni–Ti and Mn–Ti.