Segregation of Cr at tilt grain boundaries in Fe–Cr alloys: A Metropolis Monte Carlo study

In this work, the Metropolis Monte Carlo (MMC) method employing the isothermal–isobaric statistical ensemble is applied to investigate segregation at grain boundaries in bcc Fe–Cr alloys with varying Cr content from 5 to 14 at.%. Several different 〈1 1 0〉 tilt grain boundaries, namely: Σ19{3 3 1}, Σ9{2 2 1}, Σ3{1 1 1}, Σ3{1 1 2}, Σ11{1 1 3}, Σ9{1 1 4} with misorientation angle varying in the range 26–141° were considered. Systematic MMC simulations were performed employing a two band empirical many-body potential in the temperature range 300–900 K. It was found that the binding energy of substitutional Cr to the GB core is essentially determined by the structure of the GB interface and varies in the range 0.05–0.35 eV. At this, the binding energy increases with the GB excess volume. MMC simulations revealed that either a local atomic rearrangement or segregation of Cr at the considered GBs occurs depending on the combination of temperature, alloy composition and GB structure. Influence of temperature and GB structure on the local atomic rearrangement and precipitation of α′ particles is demonstrated.