Shuffle and glide mechanisms of prismatic dislocations in a hexagonal C14-type Laves-phase intermetallic compound

Complex structured intermetallic compounds often show brittleness at ambient temperature or under high strain rate deformation, but ductility at elevated temperature or low strain rate deformation. The change of dislocation behavior plays a decisive role in the brittle-to-ductile transition. Here, dislocations are studied in a hexagonal structured Laves-phase intermetallic compound with aberration-corrected scanning transmission electron microscopy after quasistatic compression at high temperature or high-speed impact at room temperature. Different slip mechanisms are resolved for the prismatic dislocations. Under the high-temperature compression, a shuffle mechanism assisted by diffusion mediates the dislocation motion to form planar defects strictly following the topologically close-packing rules. In contrast, under the high-speed room-temperature impact, the prismatic dislocations prefer to glide on undulated planes that comprise small facets with high atom density.