First-principles calculations of energetics of sigma phase formation and thermodynamic modelling in Fe-Cr-Ni system
|Year of publication
|Article in Periodical
|Magazine / Source
|Journal of Alloys and Compounds
|MU Faculty or unit
|Transition metals; Sigma phase; First-principles calculations
|A combination of full-potential linear augmented plane-wawe (FLAPW)method (for elemental constituents) with simpler linear muffin-tin orbital method in atomic sphere approximation (LMTO-ASA (for mixtures) in density functional theory (DFT) was employed for nickel systems (Ni-Fe and Ni-Cr) to calculate the energy of formation of sigma phase with respect to standard element reference (SER) structures of pure constituents. In all cases, the optimisation of the equilibrium volume of sigma phase and of SER structures was performed. Calculated energies of formation of sigma phase with respect to SER state of pure constituents in Ni-Cr and Ni-Fe systems were compared with the results of thermodynamic modelling. Phase diagram of ternary Fe-Ni-Cr system determined with the help of ab inition calculated sigma phase parameters in pure elements are in a good agreement with experimental data. Enthalpies of formation of sigma phase in Ni-Cr and Ni-Fe systems obtained by thermodynamic modelling agree reasonably well with the energy of formation in these systems, calculated ab initio.