First-principles calculation of self-interstitial atom-impurity atom interactions in ferritic steel

Abstract

In this study, the interactions between self-interstitial atoms (SIA) and impurity atoms
(Cu and P) in the bcc-Fe matrix have been investigated using the first principles
approach. The results show that Cu and P atoms are more prone to segregation on
perpendicular and parallel surfaces containing dumbbell atoms, respectively. Next, by
combining the charge density difference and considering the electronic structure and
lattice distortion, the origin of the binding energy of complexes formed between SIA
and impurity atoms was discussed. The results show that as the number of impurity
atoms increases, the atomic bonds formed by the interactions between the impurityatoms decrease the binding energy between single impurity atoms and the matrix andreduce the strain field around them, resulting in an increase in the stability of the
complexes. Comparison with previous experimental results revealed the reasons for the
changes in atomic occupancy during the segregation of Cu and P atoms. The results
provide insights into the behavior of impurity atoms in irradiated materials and provide