It was recalled that the motion of such a dislocation occurred via kink-pair formation in a 2-dimensional Peierls potential. By using the line-tension model for a dislocation, the saddle-point configuration of a non-planar kink pair in 3-dimensional space, and the associated activation energy, were calculated. The method was applied to a <111> screw dislocation in a body-centered cubic lattice; assuming a 3-fold periodic sinusoidal Peierls potential in the (111) plane. In this potential, the dislocation could nucleate a kink pair from 1 stable straight configuration, towards any of the 3 adjacent ones. Depending upon the direction of the applied stress, the relative frequencies of the 3 activation processes governed the temperature dependence of the critical flow stress and the direction of total slip. The calculations predicted well the plastic anisotropy of body-centered cubic transition metals.

Motion of a Screw Dislocation in a Two-Dimensional Peierls Potential. K.Edagawa, T.Suzuki, S.Takeuchi: Physical Review B, 1997, 55[10], 6180-7