WEAK-BEAM STUDY OF [111] SUPERLATTICE DISLOCATIONS IN NIAL

Superlattice dislocations with <111> Burgers vectors, introduced in NiAl single crystals by compression at room temperature, along the [001] crystal axis, are studied by weak-beam transmission electron microscopy. It is found that slip in the <111> direction occurs in a {112} plane. Dissociation, if any, does not exceed 1.5 nm, thus establishing a lower limit for the antiphase boundary energy on {011} and {112} planes at approximately 500 and 750 mJ m-2, respectively. Double images may arise under weak-beam conditions, due to double diffraction at the core of <111> superlattice dislocations.