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Dislocation motion, constriction and cross-slip in fcc metals

1998; IOP Publishing; Volume: 6; Issue: 1 Linguagem: Inglês

10.1088/0965-0393/6/1/005

1361-651X

M. S. Duesbery,

Surface and Thin Film Phenomena

A Finnis/Sinclair-type interatomic potential for copper is used to examine the properties of dissociated screw dislocations in the face-centred cubic lattice. The critical stress for dislocation motion is found to be a sensitive function of the partial dislocation separation, with a lower limit at least 85% smaller than the Peierls stress. The constriction of Heidenreich-Shockley partials is modelled using an applied stress which interacts only with the edge Burgers vectors; recombination is not observed, but there is a critical separation below which the potential energy of the dislocation rises very rapidly. The classical model of cross-slip, in which the dislocation cannot leave its slip plane unless it is fully constricted, is found to be incorrect. Instead, cross-slip is possible at all partial separations, provided the driving stress is large enough. Finally, a new mechanism for cross-slip nucleation is described.