Deformation of Copper Single Crystals at 300°K and 78°K

Abstract

Single crystals of copper were deformed at 78\ifmmode^\circ\else\textdegree\fi{}K and 300\ifmmode^\circ\else\textdegree\fi{}K. There was slight temperature dependence of the critical shear stress in this range of temperature and for shear strains less than about 0.25 the stress-strain relationship was linear and independent of temperature. The linear relationship of the stress-strain curve persisted for higher strains at 78\ifmmode^\circ\else\textdegree\fi{}K. The annealing at 300\ifmmode^\circ\else\textdegree\fi{}K of crystals deformed at 78\ifmmode^\circ\else\textdegree\fi{}K showed a decrease in electrical resistance accompanied by a phenomenon suggestive of strain aging. The magnitude of the recoverable resistance was dependent on the strain varying at a faster rate than a linear relationship. A measurable decrease in electrical resistance was not observed for strains less than about 0.30. These results are interpreted according to the theory of dislocations and indicate some modification to the theory of work hardening suggested by Mott.