The effect of strain path and temperature on the microstructure developed in copper processed by ECAE

The microstructure of copper developed by equal channel angular extrusion (ECAE) to a strain ∼8 was investigated using different strain path and temperature. Two different strain paths were obtained by rotating the billets through 90° (route BC) or 180° (route C) between each pass. In general, the microstructure should be characterized as a cold-worked structure with varied degree of recrystallization depending on the processing route and temperature. At room temperature, both routes produced similar microstructure except the formation of recrystallized grains by route BC. By the use of route BC, the volume fraction and size of recrystallized grains were found to increase with increasing deformation temperature, while the size of recrystallized grains showed considerable increase above 150 °C. Comparing with aluminum deformed by ECAE at similar homologous temperature (∼0.32Tm), the most distinct difference in the microstructure development is the presence of dynamic recrystallization in copper.