Stair-rod-dislocation-like defects in γ′ precipitates of a deformed two-phase superalloy

Abstract

Stair-rod-dislocation-like defects (SRD-like), lying in plastically deformed L1₂ γ′ precipitates of the CMSX-2 two-phase superalloy, have been observed in transmission electron microscopy using the two-beam technique. For one of these defects a comparison between experimental bright-field images and computed images proves that the defect cannot be a SRD with a Burgers vector 1/3[0 2 0] located at the common edge of two superlattice extrinsic stacking faults, as first expected from an inspection of a fringes. From computed images, it is shown that the total elastic field of the defect is close to that of a dislocation with a Burgers vector 1/3[0 1 0].