Effect of boron and sulphur on the electronic structure of grain boundaries in Ni

Abstract

The first-principles discrete variational method is employed to study the effect of boron and sulphur on the electronic structure of the Ni Σ11(1 1 3 ̄ )/[1 1 0] grain boundary (GB). The calculated results show that boron does not strongly influence (only slightly decreases) the bonding between the atoms of the metal. In addition, B forms the strong bonding state with its neighbouring metal atoms. Our study also indicates that S strongly decreases the bonding between the atoms of the metal, and that the bonding tendency between S and the atoms of the metal across the GB plane is very weak. The calculations of environment-sensitive embedding energies show B has the strong site-competition ability and can successfully drive out S from the GB region. We conclude that the influence of impurities segregating on the GBs is closely associated with their effects on: (i) the decrease of the bonding between the atoms of the metal due to the presence of impurities; (ii) the bonding between the impurity atom and the atoms of the metal; and (iii) the site-competition ability of impurity atoms.