First-principles study of FeNi1-xCrx (0≤x≤1) disordered alloys from special quasirandom structures

Abstract

Using a combination of first-principles calculations, special quasi-random structures and quasi-harmonic Debye model methods, we investigated the structural properties, magnetic moments, phase stability, electronic structure, mechanical properties and thermodynamic properties of fcc and bcc FeNi1-xCrx disordered alloys. The results show that the volume per atom and lattice constant of fcc and bcc FeNi1-xCrx alloys exhibit different nonlinear decreasing trends with increasing Cr content, which can be understood by the coupling effect of the composition-dependent antiferromagnetic interaction and atomic volume. Only fcc FeNi1-xCrx alloys with x less than 0.25 are relatively easy to synthesize, while FeNi1-xCrx alloys with other compositions all have a strong tendency to phase separation. The DOS of fcc and bcc FeNi1-xCrx alloys gradually moves to the shallower energy level with the increase of Cr content, which makes TDOS narrow. As the Cr content increases, the hardness and rigidity of fcc FeNi1-xCrx (x = 0, 0.125, and 0.25) alloys gradually increase, while the toughness, ductility and compression resistance gradually weaken. Increasing Cr content is beneficial to reduce the volumetric thermal expansion coefficient of fcc FeNi1-xCrx (x = 0, 0.125, and 0.25) alloys, which also can decrease Debye temperature and weaken interaction between atoms.