First-principles study on the effect of Mn and N on the cohesion of a γ-iron grain boundary

By use of the linear-combination-of-atomic-orbital (LCAO) method for a cluster model, we studied the electronic structure of {γ}-iron {Σ} 11 [110](113) grain boundary doping with N and Mn atoms. The effect of the segregation on the cohesion of the grain boundary is investigated based on the Rice-Wang thermodynamic model. It is found that N could not only largely enhance the cohesion of the grain boundary but also eliminate the detrimental effect of Mn. The cosegregation effect of Mn and N on the cohesion of the grain boundary depends on where they segregate. Nitrogen could be reliably used in alloyed steels as an efficient strengthening element.