Incomplete kear–wilsdorf barriers in Ni₃(Al, Ti)

Abstract In the L12 long-range-ordered structure, superlattice dislocation form complicated configurations and barriers. Kear–Wilsdorf (KW) barriers are screw superlattice dislocations which are totally dissociated on cube planes. The driving force for their formation is the elastic repulsion of the superlattice partials constituting the screw superlattice dislocation, balanced by a lower antiphase boundary energy on cube {001} planes compared with that on octahedral {111} planes. The striking result of this letter is the observation of screw superlattice dislocations partly dissociated on cube and octahedral planes. We call them incomplete KW barriers. Their Occurrence provides evidence that the KW barriers are products formed during deformation and not a consequence of unloading after deformation or artefacts due to specimen preparation.