Phenomenological calculation of phase equilibria in the FeNi system

In order to seek inexpensive substituting elements for Pd in an FePd based L10 ordered phase, a phenomenological calculation based on the cluster variation method combined with a Lennard-Jones type pair-wise atomic interaction energies has been attempted for a FeNi binary system. The phase equilibria for FeNi3-disorder and FeNi-disorder are investigated. In particular, a tetragonal distortion is explicitly considered for the FeNi L10 ordered phase. The calculated FeNi3-disorder phase boundary shows good agreements with an experimental result. An FeNi L10 ordered phase which does not appear in a conventional FeNi binary phase diagram is predicted as a stable phase, implying that Ni is a potential substituting element for Pd in an FePd based L10 ordered phase.