Investigation on properties of FeNi intermetallics under pressure by First-principles

Abstract

In this paper, the structural stabilities, elastic, electronic and magnetic properties of three binary Fe-Ni intermetallics with different structure under pressure have been systematically investigated by first-principle method based on density functional theory. The results indicated that the lattice parameters and bulk modulus of Fe-Ni compounds at zero pressure match well with other experimental data and available theoretical calculated values. The calculated energy-volume and pressure-volume expressed that all the compounds are mechanical stability under pressure, and the volume variation increase with the increasing iron content under pressure. The shear deformation resistant and volume deformation resistant are estimated by elastic constant Cij and bulk modulus B. Meanwhile, applied pressure improved the ductility of the Fe-Ni compounds, elastic anisotropy of three compounds under pressure are arranged in the following order: Fe3Ni>FeNi>FeNi3. Debye temperature ΘD of compounds gradually increase with the increase of iron contents and pressure, the temperature dependence of the linear thermal expansion coefficient α and heat capacity (CV and CP) are also calculated based on quasi-harmonic Debye model under pressure from 0 to 50GPa and various temperature. The results gain a better understanding of iron-nickel alloys.