Thermodynamic calculation on the stability of (Fe,Mn)3AlC carbide in high aluminum steels

A CALPHAD type thermodynamic description for the Fe–Mn–Al–C quaternary system has been constructed by combining a newly assessed Mn–Al–C ternary description and a partly modified Fe–Al–C description to an existing thermodynamic database for steels. A special attention was paid to reproduce experimentally reported phase stability of κ carbide in high Al and high Mn steels. This paper demonstrates that the proposed thermodynamic description makes it possible to predict phase equilibria in corresponding alloys with a practically acceptable accuracy. The applicability of the thermodynamic calculation is also demonstrated for the interpretation of microstructural and constitutional evolution during industrial processes for high Al steels.