Double-kink generation in 3-fold screw dislocations in body-centered cubic crystals was studied within the framework of the generalized Peierls-Nabarro model, in which partial dislocations were described by non-singular displacement fields. The kink geometry was modelled by dividing the dislocation into elemental slabs; each of which was assumed to have its own 2-dimensional displacement field which was calculated by using the Peierls-Nabarro model. The apparent activation energy was predicted to vary with the stress in an approximately parabolic manner, and was found to be in good agreement with experimental findings for a wide range of body-centered cubic metals. The interaction between a 3-fold screw dislocation core and a mode-III crack tip was also investigated, and the results suggested that the dislocation mobility was somewhat reduced ahead of a crack tip.

Modelling Screw Dislocation Mobility in the Bulk and in the Vicinity of Crack Tips using a Peierls-Nabarro Approach. A.H.W.Ngan: Key Engineering Materials, 2000, 177-180, 135-40