Atomistic study of the effect of B addition in the FeAl compound

First principle calculations have been carried out to study energetic of boron atom impurities in bulk and symmetric Σ5(310) tilt grain boundaries of the ordered stoechiometric B2 FeAl intermetallic. A set of configurations was considered for studying the bulk behaviour: B in tetrahedral and octahedral interstitial positions or substituting Al and Fe. For the analysis of the segregation at the grain boundary, calculations were done for B substituting Al and Fe at three different locations and for B filling empty spaces along the interface. In each case, the defect formation energies were calculated to determine the site preference and their relative stability. The results indicate that B doping is metastable in the bulk and tends to segregate along the grain boundary. The overall behaviour of the B atoms at the boundary is essentially driven by the strong Fe–B interactions.