Strengthening of copper by dislocation substructures

Substructural strengthening in pure copper deformed by cold rolling is shown to depend on both the mean free path and the level of nonuniform strain associated with the dislocation substructure. Contributions from the nonuniform strain are particularly important because the mean free path becomes constant after deformations of ∼50 pct R.A., whereas the material continues to work harden. The behavior of the nonuniform strains at large deformations is also found to be closely related to dynamic recovery. Development of an empirical expression for the strengthening in terms of the substructural parameters is shown to lead to a modified Hall-Petch type relation. W. G. TRUCKNER formely Graduate Student, Michigan Technological University is now at Alcoa Laboratories, Alcoa Center, PA 15069.