By using first-principles calculations, grain boundary decohesion (embrittlement) in ferromagnetic body-centered cubic Fe Σ3(111)[1¯10] and face-centered cubic Ni Σ5(012)[100] symmetrical tilt grain boundaries was simulated by progressively adding S atoms to the boundaries. The segregation energy of S atoms, tensile strength and cohesive energy of the grain boundaries were calculated. It was shown that a certain amount of S segregation (two atomic layers, 14.4atom/nm2) was energetically possible; considering the calculated segregation energies. At this concentration, the tensile strength and the cohesive energy of the grain boundaries were reduced by an order of magnitude as compared with the no-segregation case.

Grain Boundary Decohesion by Sulfur Segregation in Ferromagnetic Iron and Nickel - a First-Principles Study. M.Yamaguchi, M.Shiga, H.Kaburaki: Materials Transactions, 2006, 47[11], 2682-9