The distribution of chromium between ferrite and austenite and the thermodynamics of the α/γ equilibrium in the Fe-Cr and Fe-Mn Systems

New measurements of the α/γ equilibrium in the Fe-Cr system are presented and all the relevant experimental information now available, including thermodynamic data, is evaluated using a regular solution model. The two-phase field is calculated in good agreement with most of the experimental measurements. The point of minimum is obtained at 1119 K and 7.0 at. pct Cr (6.6 wt pct Cr) and the maximum solubility in austenite is 11.9 at. pct Cr (11.2 wt pct Cr). The thermodynamic quantities describing the effect of chromium on the relative stability of ferrite and austenite are similar to those for manganese. The comparison is based upon a new evaluation of the Fe-Mn system. In particular, low chromium contents are found to have a stabilizing effect on austenite up to a temperature of 1675 K.