DISLOCATION-STRUCTURE AND DENSITIES IN TENSILE DEFORMED CUMN CRYSTALS ORIENTED FOR SINGLE GLIDE

A systematic TEM study is presented of the dislocation structure and density in tensile-deformed Cu-1.3at%Mn crystals oriented for single glide. Due to missing short-range order no planar glide is observed. As in crystals of pure Cu primary and secondary dislocations arrange in bundles. In the extended stage I the strain hardening rate decreases with increasing strain, the primary dislocation density being already very high. Along the stress-strain curve only the secondary dislocation density, but not the primary one, follows the well-known quadratic relation, rho(sec) approximately (tau - tau(0))2. The total strengthening is described by a linear superposition of hardening by the Mn atoms and by the forest dislocations.