The influence of an elastic stress on the electrical resistance of copper after plastic deformation

Abstract

Thin wires were plastically deformed at −195°C, after this deformation the electrical resistivity is increased. This increase disappears after recovering at higher temperatures. During isothermal recovery, an elastic stress of about 15 kg/mm 2 was applied to or removed from the wire, causing an extra decrease of the electrical resistance. Thus the change of stress is essential for the decrease of the resistivity. The elastic stress was varied in different ways, sometimes in combination with temperature variations. The results are very sensitive to the details of the experimental method. Mainly pure copper was used, sometimes gold, silver and aluminium. Most of the results can be explained with the following hypotheses: 1. (1) As a result of changing the stress the dislocations bend out, and eliminate some dislocation loops or other configurations, causing a decrease of the electrical resistance. 2. (2) Point defects moving toward the dislocations can pin them. This pinning is dependent on the temperature and on the stress. 3. (3) Point defects moving toward the dislocations can give some dislocation climb, which enables the dislocations once more to take up some loops by bending out, if in the old positions the attainable loops have already been eliminated.