Computer simulation of grain boundary in BCC Fe by embedded atom method

Structures and energies of the symmetric grain boundaries with the value of Sigma ranging from Sigma 3 to Sigma 33 tilted about the [011] axis, Sigma 5 tilted about the [001] axis and Sigma 7 tilted about the [111] axis in bcc iron are investigated by molecular mechanics method with the embedded atom potential of M.W.Finnis and J.E.Sindair with consideration of relaxation in directions both perpendicular and parallel to the grain boundary. Some kinds of stable and metastable structures are obtained for these grain boundaries. The energies of the grain boundaries with lower value of Sigma such as Sigma 3, Sigma 5 and Sigma 7 are lower than those with rather higher value of Sigma such as Sigma 19a, Sigma 27a and Sigma 33a. Grain boundary energy is considerably decreased by relative displacement of the two crystals sandwiching the grain boundary in the directions parallel to it. Grain boundary energies calculated with the embedded atom potential of M.W.Finnis and J.E.Sinclair are roughly 20% greater than those calculated by D.Wolf with a Johnson type potential.