Thermodynamic modeling of the Cr – S system

Abstract

Abstract All known phases of the chromium – sulfur binary system have been taken into consideration within a thorough thermodynamic analysis of phase equilibria and thermodynamic data at 1 bar total pressure over the entire composition range between 25 °C and temperatures above the liquidus. Gibbs energy modeling for ten phases has been performed. A limited set of model quantities were optimized by which the experimental data can be reproduced simultaneously within experimental limits of error. New interpretations of complex phase relations are obtained. The extended modified quasichemical model is applied for the liquid chromium – sulfur phase. The Gibbs energy of high-temperature chromium pyrrhotite solution is described by a two-sublattice model within the framework of the compound energy formalism. The sulfur solubility of solid chromium is modeled using a substitutional approach. The Gibbs energies of six stoichiometric compounds are also modeled. The first internally consistent description of all thermodynamically stable phases known in the literature for the chromium – sulfur system is presented.