Computer Simulation of Motion of a Screw Dislocation in BCC Crystals Using Finnis-Sinclair Potential

Motion of a screw dislocation in a bcc lattice has been investigated by computer simulation technique using Finnis-Sinclair potential (Ta). Motion under pure phear stress was compared with that under both shear and normal stress, i. e., conventional tensile condition. It was made clear that existence of normal stress reduced critical shear stress, i. e., Peierls stress for a screw dislocation. The total energy change was calculated during the screw dislocation motion overcoming Peierls potential, and sh6wed double peaks of the total energy exist within one atomic distance motion. This showed that Peierls potential has a camel－hump shape (double peak shape), which is desirable to explain the characteristic temperature dependence of the yield stress observed in bcc metals