Thermally activated motion of screw dislocations in B.C.C. metals

The splitting of a 1/2 〈111〉 screw dislocation on one and three {110} planes, and on one and two {112} planes is assumed. It is proposed that repeated mutual transformations of these splittings during the motion of a screw dislocation control its thermally activated motion. Activation energies of these transformations are calculated as functions of the stacking fault energy, the external shear stress, and the orientation of the maximum resolved shear stress plane. The velocity of a screw dislocation is then calculated by the usual rate theory.