The origin of dislocations and sub-structure arrangements in copper single crystals

Abstract
The density and distribution of dislocations in copper single crystals solidified at various rates were studied by an etch-pit technique. The overall density was found to be nearly constant over the range of growth rates used (1·25 to 15·0 cm per hour), and the sub-grain diameter was observed to increase markedly as the growth rate increased. The results are shown to be incompatible with the collapsing of vacancy discs as a mechanism for the origin of dislocations while consistent with the concepts of dislocation nucleation by impurities. The dislocation distribution variation with growth rate is associated with the time available for dislocation climb behind the solid-liquid interface.