The deformation of single crystals at 4.2K was studied by making simultaneous measurements of mechanical and electrical properties, with the aim of extending the study of low-temperature deformation to higher strains than those normally used. Most of the crystals were stretched to failure. The deformation could be divided into 3 distinct regions. In region-A, which included stages I and II of plastic deformation, the crystal deformed by slip. In region-B, there was twinning but no slip. At the end of region-B, the specimen was 70% twinned. The crystal entered region-C as a fine-layer structure which consisted of twin and parent lamellae. In this region, there was no more twinning and deformation proceeded via slip. An examination of the deformation-induced resistivity, and its annealing, confirmed that the flow stress in region-A was due to dislocation accumulation and indicated that, in region-C, other obstacles (such as twin/parent interfaces) were also important. The annealing data, and other evidence, suggested that the elimination of short vacancy dipoles and loops via pipe diffusion accounted for the recoverable component of the resistivity.

Deformation of Copper Single Crystals to Large Strains at 4.2K - I. Mechanical Response and Electrical Resistivity. M.M.Niewczas, Z.S.Basinski, S.J.Basinski, J.D.Embury: Philosophical Magazine A, 2001, 81[5], 1121-42