Three types of dislocation core structure in B2 alloys

• The stacking-fault-like defects in YAg are analysed.
• A mesoscopic model for dissociated total dislocations is developed.
• Various types of superlattice dislocation in different B2 alloys are classified.
• Dislocation behaviour controls ductility of B2 rare-earth alloys.

The mechanical properties are directly influenced by the properties of dislocation. In the relatively simple ordered structure of B2 type, the dislocation core structure is controlled by the stacking-fault-like defects as antiphase boundaries. It will be shown, that three types of B2 alloys can be distinguished differing by the degeneracy of antiphase-boundary-like defects energies on the {110} plane: crystallographic, two- and four-fold degenerated antiphase boundary energies. Various types of superlattice dislocation and their impact on dislocation mobility is discussed in this paper.