A strain-rate dependent mechanism was described for cooperative dislocation generation in loaded solids above a critical temperature. Massive dislocation activity which began near to the crack tip at the brittle-ductile transition temperature was modelled in terms of this mechanism. It was concluded that the strain-rate dependence of the critical temperature arose from the glide of pre-existing dislocations and of dislocations which were thermally nucleated below the critical temperature via the above cooperative process. Depending upon their relative contributions, the apparent activation energy which was associated with the brittle-ductile transition temperature was equal to, or larger than, the activation energy for dislocation motion.

Strain-Rate Dependent Mechanism of Cooperative Dislocation Generation - Application to the Brittle-Ductile Transition. M.Khantha, V.Vitek, D.P.Pope: Materials Science and Engineering A, 2001, 319-321, 484-9