A comparative study of dislocation core structures was carried out on B2 compounds. The dislocation cores were studied using atomistic computer simulations and embedded-atom method potentials. The results revealed a marked dependence of the core structure upon the antiphase-boundary energy of the compound. The <111> screw dislocations were found to have planar cores in {110} planes. For very high antiphase boundary energy values, the cores were very compact. As the antiphase boundary energy decreased, an increase in 2-dimensional spreading of the cores was observed and the dislocation ultimately dissociated into partials. The latter were not exact ½<111>, but corresponded to the actual minima of the γ surfaces for these compounds. It was shown that the dislocation cores could be best described as being partly dissociated into partials, with a continuous transition from dissociated to undissociated structures occurring as the planar fault energy increased. This contradicted the view that dislocations were either dissociated or undissociated in a distinct sharp transition.

Transition from Dislocation Core Spreading to Dislocation Dissociation in a Series of B2 Compounds. C.Vailhé, D.Farkas: Philosophical Magazine A, 1999, 79[4], 921-31