First-principles investigation of the effect of alloying elements Ti, V on grain boundary cohesion of FCC Fe

The discrete variational and Dmol methods within the framework of density functional theory are used to study the effects of Ti and V on the electronic structure of ∑11[11̄0](113) grain boundary in FCC Fe. The results show that both Ti and V prefer to segregate at grain boundary. The differences of segregation energies between the grain boundary and the corresponding free surface are -0.12 and -0.36 eV for solute Ti and V, respectively. According to Rice-Wang model, our results imply that both Ti and V enhance the grain boundary cohesion in FCC Fe. This work also shows that the effects of Ti and V on the bonding behavior are different. When Ti segregates at grain boundary, the bonds across grain boundary are strengthened, while the interactions between Ti and its neighboring atoms are weakened. But for V-doped grain boundary, V interacts with its neighboring atoms stronger than that of clean grain boundary and V also makes the bonds across the grain boundary stronger.