Binding and unbinding of 2 threading dislocations in a channel of width, d, was considered within the context of the persistent slip band problem. It was shown that previous analytical estimates of the overall passing stress between 2 screw-like threading arms were only qualitatively correct. That is, previous treatments did not recognize the importance of bowing corrections in all limits, and neglected the effects of the misfit arms of the opposing dislocation upon the passing-stress. As an alternative, accurate numerical escape functions were presented for the case of d = 1μm, in a form suitable for approximate scaling to other values of d. Although the numerical prediction for the overall passing stress was in good agreement with experimental values of the flow stress observed in the presence of persistent slip bands, it was argued that this represented a disagreement, since it was well known that the flow stress in the soft-channel parts of the inhomogeneous persistent slip band structure was reduced by long-range internal back stresses to values which were significantly below the average macroscopic flow stress of the persistent slip band structure. It was suggested that a statistical treatment which included the effects of annihilation, and of dislocations interacting over a range of separations, could account for the discrepancy.

Interaction and Passing Stress of Two Threading Dislocations of Opposite Sign in a Confined Channel. K.W.Schwarz, H.Mughrabi: Philosophical Magazine Letters, 2006, 86[12], 773-85