Calculation of the phase energy in Fe-Ni alloy with modified embedded atom method

The modified embedded-atom method (MEAM) was used to systematically study the order and disorder phases with fcc or bcc structure in Fe-Ni alloys, in which the relationship between the content of Ni and the probability for an atom occupying a lattice point was introduced to compute the energies of disorder phases. The calculated results indicate that the equilibrium concentrations of the two disorder phases, α (bcc) and γ (fcc), are 8.6% Ni and 31.5% Ni at 347°C respectively, which is basically coincident with the Fe-Ni phase diagram. It is expected that FeNi3 should exist in the most stable state, the following is FeNi and the last is Fe3Ni. Their stability agrees with the experimental results reported in literatures.