The effect of Re segregation on the α-Fe Σ5 [001] (010) grain boundary was investigated by using a software called DMol and discrete variational method. Based upon the Rice–Wang model, the calculated segregation energy and defect formation energy showed that Re was a strong cohesive enhancer. The interatomic energy and bond order of several atomic pairs were also calculated in order to investigate the mechanism of the cohesive effect of Re microscopically and locally. The results showed that the interatomic energies of atomic pairs formed by those atoms which cross the plane of a grain boundary were strengthened due to the segregation of Re, while the bond orders of the corresponding pairs were slightly decreased. This discrepancy demonstrated that an interatomic energy which contained the Hamiltonian of interaction between atoms was a good quantity to describe the bonding strength. The analysis suggested that the electronic effect between atomic pair which comes directly from Hamiltonian was the key factor. The charge density was also presented and the result indicated that the bonding strength between the Fe atoms on the grain boundary was enhanced due to the segregation of Re, which was consistent with the analysis of interatomic energy.

Effect of Element Re on the Grain Boundary Cohesion of α-Fe. Z.Z.Chen, C.Y.Wang: Chinese Physics, 2006, 15, 604-9