Asymmetrical equilibrium postions and line tensions of composite dislocations

Using anisotropic elasticity theory, the extensions of dislocation locks of the type Lomer-Cotrell (LC, B4) and Hirth (HL, B2) are calculated by minimizing the elastic interaction energy and the stacking fault energy of the configuration. Contrary to previous results the barriers LC and B2 are found to have asymmetrical equilibrium positions. The asymmetry is produced by the angular force components of the partial dislocations. Line energies and line tensions of recombined locks are determined as a function of dislocation orientation in the glide planes where they move conservatively. As a enosequence of anisotropy specific orientations of the barriers possess negative line tensions, reducing their stability.