Dissociation and motion of dislocations in a C14 Laves phase

Abstract

Laves phases are typical complex intermetallic compounds, and the mechanisms governing dislocation motion within these crystals remain poorly understood. In this study, we employed aberration-corrected scanning transmission electron microscopy to directly observe the dissociation and movement of <c+a> dislocations in a hexagonal C14 Laves phase subjected to high-temperature compression. These dislocations exhibit multiple dissociations, with their behavior shifting from being controlled by long-range lattice translational order to short-range configurations associated with local atomic environments. A twin-synchroshear mechanism is proposed to promote the migration of multilayer atoms during the 1/6<2-203> dislocation climb on basal planes. Our experimental findings in the C14 Laves phase suggest that the most effective plastic deformation in complex structures arises from dislocations that facilitate local structural transformations while maintaining long-range lattice order. This insight advances our understanding of dislocation behavior and plasticity in complex intermetallic compounds.