Core Structure and Motion of Metadislocations in the Orthorhombic Structurally Complex Alloy Al13Co4

The atomic structure of metadislocation cores in the phase o-Al13Co4 is investigated using aberration corrected scanning transmission electron microscopy. Metadislocations with Burgers vectors of -b/tau(4) [0 1 0] and b/tau(3) [0 1 0] having six and four stacking faults, respectively, are found. They are associated with separate phason defects, which escort the movement of the metadislocations through the material. A first partial atomic model for metadislocation glide motion, taking Cobalt atom jumps into account, is developed. Atom jumps take place in pairs along various crystallographic directions. Typical jumps occur between atomic columns separated by 1.5 angstrom.