A brief reply to comments on: 'Constant intermittent flow of dislocations: central problems in plasticity

摘要

Professor Dimiduk (personal communication) points out that submicrometre diameter crystals produced by focused ion beam milling show in compression extraordinarily high flow stresses and extensive plastic strain with work hardening rates comparable to those of stage I in macroscopic single crystals. Work by his group emphasises the intermittent nature of the flow and correlates the sudden appearance of slip bands traversing the crystal with displacement bursts. Although the magnitude of the plastic strain is in keeping with Fourie's earlier results on much larger crystals, the high flow stress is not. It seems likely that the microcrystal behaviour results from the high stress required to operate single-ended, truncated, Frank-Read sources in the very small crystals, combined with the progressive exhaustion of sources whose supply is limited by comparison with Fourie's.5"6 Fourie's results relate more directly to surface effects in the work hardened defect structure of macroscopic crystals.