Embedded atom method potentials for Si and Nb as alloying elements in Fe

Silicon (Si) and niobium (Nb) are chemical elements added to iron (Fe) alloys to improve their mechanical properties. In this work, we present a simple protocol for obtaining empirical interatomic potentials, based on the Embedded Atom Method (EAM) formalism, for these alloying elements within the dilute limit (i.e., solute concentration typically below 1 at.%), using a potential already established for the matrix element, which was not refitted. The potential functions for Si and Nb were fitted to first-principles data where the alloying elements entered as substitutional impurities in the body-centered cubic (bcc) lattice of Fe. In addition to the distortion of the lattice caused by the insertion of Si or Nb, the interaction energies with point defects, such as vacancies and other Si or Nb atoms, were also included. Reasonable agreement was observed when comparing the results obtained with the EAM potentials with first-principles data not used in the fitting procedure (e.g., migration energies of Si and Nb by the vacancy mechanism). The new Fe-Si and Fe-Nb potentials are not intended to simulate the stable phases of the alloying elements individually, nor Si-and Nb-rich phases, such as the Fe 2 Si compound and the Fe 2 Nb Laves phase.