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

Abstract

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.