Gittergeometrische Betrachtung der plastischen Verformung von Lavesphasen

The brittleness of many intermetallic compounds even of those of metallic bond is supposed to be related to the lattice geometry. The influence of the arrangement of atoms on slip of dislocations has been investigated in case of the Laves phase lattices of MgZn₂ (C 14)- and MgCu₂ (C 15)-type of structure and is compared with the close packed lattices of metallic elements. Changes of coordination during slip, interpenetration of lattice planes in a hard sphere model, possible stacking faults, and partial dislocations have been considered. From there the most favourable slip planes are derived for dislocations of the following characters: perfect dislocations of stable Burgersvectors and Burgersvectors indifferent to dissociation and imperfect dislocations. The formation of interstitial atoms during intersection of moving edge dislocations is suggested. In comparison with the elemental lattices the brittleness of compound lattices is concluded to be a consequence of the complicated arrangement of atoms.