The Cyclic Hardening of Copper Single Crystals

Copper single crystals hardened by cyclic straining at low amplitude have been sectioned parallel to and perpendicular to the primary slip-plane. The detailed dislocation arrangements were determined by transmission electron microscopy and the surface slip behaviour observed by optical replica techniques. The results indicate that the hardening process is caused predominantly by the accumulation of dislocation debris in the form of complex braids of dipoles and monopoles and that it exhibits numerous features similar to Stage-I unidirectional hardening. These microstructural observations provide a rationale for many of the properties of cyclically hardened materials.