title: Sessile dislocations by reactions in NiAl severely deformed at room temperature.
abstract: B2 ordered NiAl is known for its poor room temperature (RT) ductility; failure occurs in a brittle like manner even in ductile single crystals deforming by single slip. In the present study NiAl was severely deformed at RT using the method of high pressure torsion (HPT) enabling the hitherto impossible investigation of multiple slip deformation. Methods of transmission electron microscopy were used to analyze the dislocations formed by the plastic deformation showing that as expected dislocations with Burgers vector [Formula: see text] carry the plasticity during HPT deformation at RT. In addition, we observe that they often form [Formula: see text] dislocations by dislocation reactions; the [Formula: see text] dislocations are considered to be sessile based on calculations found in the literature. It is therefore concluded that the frequently encountered 3D dislocation networks containing sessile [Formula: see text] dislocations are pinned and lead to deformation-induced embrittlement. In spite of the severe deformation, the chemical order remains unchanged.
authors: University of Vienna, Faculty of Physics, Physics of Nanostructured Materials, 1090 Vienna, Austria.
authors: D
authors: D
authors: Geist
authors: University of Vienna, Faculty of Physics, Physics of Nanostructured Materials, 1090 Vienna, Austria ; National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors: C
authors: C
authors: Gammer
authors: University of Vienna, Faculty of Physics, Physics of Nanostructured Materials, 1090 Vienna, Austria.
authors: C
authors: C
authors: Rentenberger
authors: University of Vienna, Faculty of Physics, Physics of Nanostructured Materials, 1090 Vienna, Austria.
authors: H P
authors: HP
authors: Karnthaler
keywords: 3D dislocation networks; B2 intermetallic compound; Deformation-induced embrittlement; High pressure torsion; Transmission electron microscopy