Quantum chemical study of sulfur and hydrogen at the Σ=5 BCC Fe grain boundary Original Research Article

We investigate the effect of segregated atoms on metal–metal bonding at a grain boundary (GB). The structure and electronic properties of S and H impurities in Fe Σ=5 (013) [100] symmetrical tilt GB are studied using the atom superposition and electron delocalization molecular orbital (ASED-MO) theory. A large cluster containing 196 Fe atoms is used to simulate the local environment of the boundary. The results show that impurities induce large relaxation in the GB and that the GB gives rise to an energetically favorable zone for the H and S accumulation. No S–H association is found and the deleterious effect of H is of much less important as compared with S.