Stability of Dislocation Short-Range Reactions in BCC Crystals

The stability of short-range reactions between two dislocations of parallel line vectors which glide on two parallel slip planes in BCC crystals is determined. The two dislocations are assumed to be infinitely long, and their interaction is treated as elastic. The interaction and self-energies are both computed for dynamically moving dislocations, where the dependence on dislocation velocity is taken into account. The stability of the reaction is determined as a function of the following phase space variables: relative angle, relative speed, dislocation mobility, Burgers vector, separation of slip planes, and external force. It is found that the dynamic formation of dislocation dipoles or tilt wall embryos occurs only over a small range of the investigated phase space. Inertial effects are shown to be important at close separation, because of the large force between the two dislocations comprising the dipole or tilt wall embryo. Destabilization of the dislocation dipoles or tilt wall embryos is found to be enhanced by externally applied stresses or by stress fields of neighboring dislocations. * Part of this work was carried out by Lawrence Livermore National Laboratory under the auspices of the US Department of Energy under contract W-7405-Eng-48