Strain hardening behaviour and deformation kinetics of Cu deformed by equal channel angular extrusion from 1 to 16 passes
Abstract
The work hardening rate, strain rate sensitivity and the apparent activation volume of copper processed by equal channel angular extrusion (ECAE) for 1-16 passes are investigated. Constant strain rate and strain rate jump tests performed in compression up to 30% of strain reveal stage III and IV work hardening for specimens subjected to less than 4 passes of ECAE, while specimens subjected to more than 4 passes show the additional occurrence of stage V work hardening. The length scale deduced from activation volume measurements corresponds with the distance of dislocations measured within dislocation walls. This suggests that the rate-controlling mechanism is the interaction of lattice dislocations with dislocations in the cell walls or subgrain boundaries and/or the mutual interaction of cell wall/subgrain dislocations. A hyperbolic function accounting for the rate-controlling deformation mechanism is proposed in order to account for the possibility of backwards fluctuations within the cell walls.
- Publication:
-
Acta Materialia
- Pub Date:
- 2006
- DOI:
- 10.1016/j.actamat.2005.10.041
- Bibcode:
- 2006AcMat..54.1135D
- Keywords:
-
- ECAE;
- Ultrafine-grained;
- Work hardening;
- Strain rate sensitivity;
- Activation volume