Dislocation patterns, and the corresponding strain rate versus time plots, showed that interactions between mobile point defects and dislocations resulted in the migration of point defects to dislocations and to the formation of point defect atmospheres around dislocations. At very high external stresses, the dislocations moved and were not captured by point defects. Therefore, a stationary strain rate was observed. It was shown that a high external stress dominated dislocation motion and prevented the formation of well-defined dislocation structures. However, as the external force was decreased (if the applied force was sufficient to overcome the anchoring effect of point defects) the dislocations could still move and leave their atmospheres behind; before being recaptured again by the atmosphere. This resulted in a sinusoidal strain-rate response during deformation. It was noted that, as the external force was decreased, the strain rate decreased and the fundamental frequency increased. Under low external stresses, the dislocations were frequently recaptured by the anchoring effect of point defects. This resulted in clusters of dislocations, in atmospheres that were separated by relatively dislocation-free regions, and led to a cell-like structure. The effects of point defect mobility upon dislocation structures during deformation had distinct characteristics and were easily identifiable. At low point-defect mobilities, the point defects could not move quickly enough to capture dislocations, and trapped only dislocations which were on the same slip plane. Thus, fewer dislocations were trapped by point defects, and the dislocations continued to move. This resulted in higher strain rates, and to no well-defined dislocation structure. At high point-defect mobilities, the dislocations were recaptured by atmospheres during deformation; thus resulting in low mobile dislocation densities and strain rates. It was shown that, as the defect mobility was increased, the strain rate decreased and the fundamental frequency increased; thus reflecting the occurrence of dislocation recapture by point defects. Captured dislocations with the same sign tended to form walls, while dislocations of opposite sign tended to form dislocation dipoles during deformation. Between dislocation clusters, dislocation-free regions were observed which indicated the presence of a cell-like structure.

Simulation of Dislocation Configurations in the Presence of Mobile Point Defects. A.N.Gulluoglu: Scripta Materialia, 1997, 36[1], 123-8