First-principles investigation of L10-disorder phase equilibria of Fe–Ni, –Pd, and –Pt binary alloy systems

Abstract

FLAPW total energy electronic structure calculations are combined with cluster variation method in order to perform first-principles investigation of phase equilibria for three kinds of Fe-based binary alloy systems, Fe–Ni, Fe–Pd, and Fe–Pt. A particular focus of the present investigation is placed on L10-disorder phase equilibria. The lattice vibration effects are incorporated within the quasi-harmonic approximation via Debye–Gruneisen model. The ground state analysis revealed that magnetism plays a crucial role in the phase stability of each system. The calculated transition temperatures for Fe–Pd and Fe–Pt systems are in close agreement with experimental ones. The lattice vibration effects further improves the accuracy, and it is found that magnetic fine structure also affects the resultant transition temperature in Fe–Pt system. Although L10-ordered phase does not appear as a stable ordered phase in a conventional phase diagram of Fe–Ni system, the present first-principles calculation suggests the possibility of the stabilization of this phase. The effect of the second nearest neighbor pair interactions as well as multibody interactions are investigated.