Predictive computations of intermetallic σ phase evolution in duplex steel. I) Thermodynamic modeling of σ phase in the Fe-Cr-Mn-Mo-Ni system

Thermodynamic modeling of the a phase was revised according to the three sublattice model developed for the Fe-Cr system (Fe,Cr)(10)(Fe,Cr)(4)(Fe,Cr)(16) in the view of simulating thermodynamics and kinetics for duplex stainless steels. The alloying elements Mn, Mo and Ni relevant in duplex steels were added to the sigma phase model and their thermodynamic parameters were optimized. As sigma consequence of the change of thermodynamic model and parameters for the a phases, alloy phases were also re-optimized. The present work include re-optimization of binaries and ternaries sub-systems in order to build a consistent bottom-up Calphad dataset for the thermo-kinetic simulation of duplex steels.