Properties of dislocations in B2-NiAl have been studied atomistically using
an embedded atom potential. The response of dislocation cores to applied h
omogeneous shear stresses is investigated and the Peierls stresses of strai
ght dislocations are determined. The results are in many details in excelle
nt agreement with experimental observations. Specifically, the behaviour of
the [1 1 1] dislocations, their slip planes, cross-slip behaviour and the
limiting role of the screw dislocation can be explained. Similarly, the app
earance of the {2 1 0} plane as a secondary slip plane for the [1 0 0] disl
ocations can be rationalised. Furthermore, the interaction of the dislocati
ons with structural point defects is studied. Comparison with the flow stre
ss of off-stoichiometric NiAl from the literature shows that the individual
point defects cannot be made responsible for the strong increase of the fl
ow stress, suggesting that more complex defect structures may play an impor
tant role. (C) 1999 Elsevier Science Ltd. All rights reserved.