Ab initio and thermodynamic study of the Cr–Re system

Abstract In this work the assessment of the Cr–Re system, using a combined ab initio and CALPHAD (CALculation of Phase Diagrams) approach, is presented. To model the sigma phase, a five-sublattice combined CEF model was applied and the present description reproduces reasonably well the previously published experimental phase diagram. Formation enthalpies of the stable/metastable configurations of the sigma phase were estimated from ab initio calculations. A comparison of results using simplified two- and three-sublattice models and the five-sublattice model for the sigma phase is also presented, which highlights differences in calculated properties as site occupancies. According to present outcomes, the five-sublattice model (Cr,Re) 2 (Cr,Re) 4 (Cr,Re) 8 (Cr,Re) 8 (Cr,Re) 8 , based on Wyckoff positions, is necessary to reproduce the atomic ordering in the sigma phase. Certain areas of the phase diagram still remain uncertain and deserve further experimental investigation.