Interatomic Fe-Cr potential for modeling kinetics on Fe surfaces

TL;DR

This paper introduces a new interatomic Fe-Cr potential based on DFT calculations, accurately modeling surface segregation and bulk properties, improving simulations of Fe-Cr alloys and aiding corrosion resistance research.

Contribution

A novel Fe-Cr potential extending previous models to include surface effects, aligning with DFT results for segregation and bulk properties.

Findings

New potential accurately predicts Cr segregation to the surface

Outperforms previous potentials in bulk property reproduction

Aligns with DFT in surface segregation behavior

Abstract

To enable accurate molecular dynamics simulations of iron-chromium alloys with surfaces, we develop, based on density-functional-theory (DFT) calculations, a new interatomic Fe-Cr potential in the Tersoff formalism. Contrary to previous potential models, which have been designed for bulk Fe-Cr, we extend our potential fitting database to include not only conventional bulk properties but also surface-segregation energies of Cr in bcc Fe. In terms of reproducing our DFT results for the bulk properties, the new potential is found to be superior to the previously developed Tersoff potential and competitive with the concentration-dependent and two-band embedded-atom-method potentials. For Cr segregation toward the surface of an Fe-Cr alloy, only the new potential agrees with our DFT calculations in predicting preferential segregation of Cr to the topmost surface layer, instead of the second layer preferred by the other potentials. We expect this rectification to foster future research, e.g., on the mechanisms of corrosion resistance of stainless steels at the atomic level.