First-principles calculations on elastic, magnetoelastic, and phonon properties of Ni₂FeGa magnetic shape memory alloys

The elastic, magnetoelastic, and phonon properties of Ni₂FeGa were investigated through first-principles calculations. The obtained elastic and phonon dispersion curves for the austenite and martensite phases agree well with available theoretical and experimental results. The isotropic elastic moduli are also predicted along with the polycrystalline aggregate properties including the bulk modulus, shear modulus, Youngs modulus, and Poissons ratio. The Pugh ratio indicates that Ni₂FeGa shows ductility, especially the austenite phase, which is consistent with the experimental results. The Debye temperatures of the Ni₂FeGa in the austenite and martensite phases are 344 K and 392 K, respectively. It is predicted that the magnetoelastic coefficient is -5.3 ×10⁶ J/m³ and magnetostriction coefficient is between 135 and 55 ppm in the Ni2FeGa austenite phase.