Metadislocation configurations and novel phason defects in the complex metallic alloy T-Al-Mn-Pd

Abstract

Metadislocations (MDs) are linear defects enabling plastic deformation in complex metallic alloys, a class of materials with large lattice parameters. We systematically investigate MD configurations in plastically deformed T-Al-Mn-Pd using aberration-corrected scanning transmission electron microscopy. Atomic-resolution imaging reveals that MDs in the T-phase can dissociate into energetically more favorable partials through a pure glide process. The analysis of MD dissociations allows for an estimate of the energy of the associated stacking faults. Adjacent MDs with opposite signs in the T-phase are found to interact and form dipolar configurations connected by shared chains of phason defects. We furthermore report on a new type of phason defect, which we identify as anti-phason. We discuss structural variants of anti-phasons, their role in the deformation- and MD-interaction processes and their energetical impact.