Composite defects in the complex metallic alloy c2-Al-Pd-Fe

We investigated plastically deformed samples of the structurally complex metallic phase c2-Al-Pd-Fe by means of transmission electron microscopy. Composite defects consisting of dislocations and associated local structural modifications were found. The dislocations trail antiphase boundaries and possess large Burgers vector moduli of 7.76 Å, which corresponds to half the lattice parameter of the c2-phase. The associated structural modifications comprise an area of 30 × 40 nm, and are identified as body-centred inclusions, structurally closely related to the face-centred c2-phase. We discuss the structural modifications as a mechanism to reduce of the total energy of the composite defects.