Thermodynamic description of solution phases of systems Fe-Cr-Si and Fe-Ni-Si with low silicon contents and with application to stainless steels

A thermodynamic optimization has been made for the solution phases of the ternary systems Fe-Cr-Si and Fe-Ni-Si in the iron-rich corner. Ternary substitutional-solution interaction parameters were optimized for the liquid, fcc and bcc phases, and the lower-order data were taken from the earlier assessed sub-systems. The calculated results were validated with experiments of phase equilibria and component activities in liquid. The new data were then added to the existing database of multicomponent steels and calculations were carried out for certain silicon containing stainless steels. As a result, clearly improved agreement was obtained between calculations and experiments concerning the liquidus temperatures and the solid/liquid partitioning of silicon in these steels.