Phase Equilibria and Thermodynamic Properties in the Fe-Cr System

Abstract

Phase equilibria and thermodynamic properties in the Fe-Cr system have been reviewed comprehensively based on experimental information and available computer simulations in different scales. The evaluated phase equilibria show significant differences from the currently accepted thermodynamic description by CALPHAD (calculation of phase diagram) approach. The thermodynamic properties of the Fe-Cr system, such as heat capacity, enthalpy, and activity, have been evaluated in reported experiments. The experiments on phase separation in the Fe-Cr system have also been critically reviewed with a focus on spinodal decomposition. The reported data are concentrated in the temperature range from 673 to 823 K. In addition, there is a transition region between spinodal decomposition and nucleation regimes within the composition limit from 24 to 36.3 at.% Cr and the temperature range between 700 and 830 K. In view of the importance of magnetism in the Fe-Cr system, some inadequacies of the currently used thermodynamic description are pointed out in addition to some problems with the current magnetic model. Remaining issues on the thermodynamics of the Fe-Cr system have been elaborated for future refinement of the thermodynamic description of the Fe-Cr system. According to the present review, the melting temperature of Cr is recommended to be about 2136 K, which is 44 K lower than the value adopted in the research community on thermodynamics, such as the Scientific Group Thermodata Europe.