The Cr-Nb-Si system: Improved thermodynamic modelling and its use in simulation of Laves phase in steel

Thermodynamic modelling of the Cr-Nb-Si ternary system is revised considering new findings in the binary Cr-Nb and extension to multicomponent systems. Thermodynamic model parameters of intermetallic phases are re-optimized based on density functional theory (DFT) calculations and experimental data. Particular attention was given to the transformations of Laves phase polytypes (i.e. C14 and C15). The calculated phase stabilities of technologically relevant Laves phase polytypes C14 and C15 are discussed. Their extension to multicomponent systems is tested for typical steel grades used in high-temperature applications. C14 is the dominant phase in high Cr ferritic steel.