Please use this identifier to cite or link to this item: https://hdl.handle.net/11499/7351
Title: Ab initio calculations of martensitic phase behavior in Ni2FeGa magnetic shape memory alloys
Authors: Soykan, C.
Özdemir Kart, Sevgi
Sevik, C.
Çagin, T.
Keywords: Elasticity
Electronic band structure
Magnetically ordered materials
Austenite
Austenitic transformations
Fermi level
Magnetic moments
Nickel
Phase behavior
Shape memory effect
Ab initio calculations
Energy calculation
Magnetic shape memory alloys
Magnetically ordered material
Martensitic phase transformations
Martensitic structures
Partial density of state
Martensitic transformations
Publisher: Elsevier Ltd
Abstract: A series of spin polarized energy calculations based on density functional theory (DFT) have been carried out to investigate the structural, magnetic, electronic and mechanical properties of Ni2FeGa magnetic shape memory alloys (MSMA's) in the austenitic and martensitic structures. We report that L21 austenitic phase is metastable at a = 5.76 Å, the NM tetragonal and 5M monoclinic martensitic structures are stable at c/a = 1.33 and c/a = 0.99, respectively. That the electron removes from Ni to Fe site during phase transformation to martensite is confirmed by the increment in the magnetic moment of Ni, while decrement in that of Fe. The analysis of the partial density of states show that some distinguishable differences in the minority spin states occur upon martensitic phase transformation, such as, the replacement of the Fe states (eg and t2g) above Fermi level by only Fe-t2g states during L21-5M transformation and the splitting of Fe-t2g states near Fermi level during 5M-NM transformation (through 7M). These changes lower the energy of the system, indicating that the final structure becomes stable. The soft tetragonal shear constant C' of the austenitic phase designates the ease of the phase transition into martensitic phase. It is shown that the results calculated in this study are in good agreement with the previous calculations and the available experiments. © 2014 Elsevier B.V. All rights reserved.
URI: https://hdl.handle.net/11499/7351
https://doi.org/10.1016/j.jallcom.2014.05.042
ISSN: 0925-8388
Appears in Collections:Fen-Edebiyat Fakültesi Koleksiyonu
Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

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