First-principle study on the segregation and strengthening behavior of solute elements at grain boundary in BCC iron

Grain boundary (GB) significantly influences the mechanical properties of metal structural materials, yet the effect of solutes on GB modification and the underlying atomic mechanisms of solute segregation and strengthening in iron-based alloys remain insufficiently explored. To address this research gap, we conducted a comprehensive investigation into the segregation and strengthening effect of 33 commonly occurring solutes in iron-based alloys, with a specific focus on the body-centered cubic (BCC) iron Σ5 (310) GB, utilizing first-principle calculations. Our findings reveal a negative linear correlation between solute segregation energy and atomic radius, highlighting the crucial role of atomic radius and electronic structure in determining GB strength. Moreover, through analyzing the relationship between strengthening energy and segregation energy, it was found that the elements Ni, Co, Ti, V, Mn, Nb, Cr, Mo, W, and Re are significant enhancers of GB strength upon segregation. This study aims to provide theoretical guidance for selecting optimal doping elements in BCC iron-based alloys.