The influence of magnetic and chemical ordering on the phase diagram of Cr-Fe-Ni

A thermodynamic dataset for the ternary system Cr-Fe-Ni which has been reported in the literature for the range from medium to high temperatures has been supplemented with datasets from the binary sub-systems at lower temperatures. The magnetic and the chemical ordering transitions which are known from the binary Fe-Ni system were extrapolated into the ternary system Cr-Fe-Ni. The phase diagram of Cr-Fe-Ni alloys at temperatures below 500 °C was predicted. The magnetic contribution to the Gibbs energy of Ni-rich alloys induces a miscibility gap which appears in the binary phase diagram of Fe-Ni as a small triangle-like field ending in a tricritical point. In the ternary system Cr-Fe-Ni the miscibility gap is present as a broad two-phase field in the vicinity of the composition FeNi3. At lower temperatures this miscibility gap participates in a sequence of changing equilibria when it interferes with the chemically ordered L12 phase.