Plastic anisotropy in b.c.c. transition metals

Motion of a 〈111〉 screw dislocation in a b.c.c. crystal has been investigated in the concept of thermally activated kink pair formation. To explain the plastic anisotropy of b.c.c. transition metals, a two dimensional Peierls potential is assumed in the (111) plane without specifying the glide plane. Using the two dimensional Peierls potential, the critical flow stress and the direction of integrated slip plane have been calculated as a function of the direction of the applied stress and temperature. The calculation with a refined Peierls potential, which has hexagonal contours around the stable positions, successfully reproduces quantitatively the plastic data of α-Fe.