Microstructure and microtexture evolution in pure metals after ultra-high straining

Ultrafine-grained, and even nanostructured materials can be manufactured by ultra-high straining by equal-channel angular pressing (ECAP), high-pressure torsion (HPT), by machining, and through combinations, such as machining of ECAP specimens, HPT plus ECAP, and HPT of machining chips. This report describes the results of investigations of the microstructure and microtexture of pure aluminium and copper subjected to different deformation processes to high imposed strains. The microstructures, dislocation densities, and microhardness developed during combinations of different strain paths were investigated and all characteristics were analyzed by X-ray, transmission and scanning electron microscopy, and by orientation imaging microscopy. The influence of different processing routes is examined in terms of the accumulated strain and microstructure refinement. A saturation in grain refinement is also considered with reference to the occurrence of recovery during ultra-high strain deformation.