Primary and secondary dislocation dipole heights in cyclically deformed copper single crystals

Copper single crystals were cyclically deformed in single slip to pre-satur ation at ambient temperature. The microstructure consisted of dense dipole bundles separated by channels with low dislocation densities. The dipole he ight in the presaturation microstructure is approximately independent of lo cation, being equal in the dipole bundles (or veins) as within the channels , for both primary and secondary dipoles. The maximum dipole heights sugges t strengths that are about a factor of two higher than the flow stress. The above observations and the consideration of thermal activation to assist t he separation of dipoles under stress suggest a homogenous stress distribut ion without internal stresses, although other interpretations are expressed in the literature. (C) 2001 Elsevier Science B.V. All rights reserved.