BSTRACTMetadislocations are novel defects recently identified in complex metallic alloys. It was reasoned that their propagation necessarily requires the orchestrated motion of hundreds of atoms along various crystallographic directions per elementary step. Here

we report on the direct observation of the motion of metadislocations on the atomic scale in the complex metallic alloy phase T-Al-Mn-Fe

using in-situ high-resolution transmission electron microscopy. We observe their propagation by discrete jumps between low-energy configurations. Using a tiling model

we determine their characteristic features including the Burgers vector

and identify their motion to take place in a mixed glide/climb process.