Regensburg 2022 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 6: Computational Materials Modelling: Defects / Alloys
MM 6.9: Talk
Monday, September 5, 2022, 18:00–18:15, H44
Ab initio study on the phase stabilities of multi-component carbides in high-Mn steels — Lekshmi Sreekala1, Jörg Neugebauer1, and •Tilmann Hickel1,2 — 1Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany — 2BAM Bundesanstalt für Materialforschung und -prüfung, Berlin, Germany
The high strength and ductility of advanced high Mn steels makes them suitable for lightweight applications in the transportation sector. A modification of their properties can be achieved by intentional or unintentional addition of further alloying elements, which is often connected with the formation of secondary phases. In particular, Cr addition improves corrosion resistance and, at the same time, inadvertently yields a substantial increase in the number of carbides precipitated, such as Fe3C and Fe23C6. Therefore, in the present work, we use density functional theory to determine the thermodynamic driving force for the formation of these multicomponent carbides by evaluating their phase stabilities. We study the free energy of formation at finite temperatures by considering the vibrational, electronic and magnetic contributions. While both Cr and Mn stabilize Fe-carbides, we found that the impact of Cr is higher than that of Mn for a typical host matrix composition of Fe, Cr and Mn. Further, we analyze the critical role of magneto-structural coupling for the phase stability of these compositionally complex carbides. Through this study, we demonstrate the predictive capability of ab initio thermodynamics to accurately describe the phase stabilities of chemically complex secondary phases in metallic alloys.