Nanostructured bulk Cu obtained by consolidation of Cu particles using equal channel angular extrusion
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abstract
Equal channel angular extrusion process was used to consolidate micro and nano copper particles (-325 mesh, and 130nm). The evolution of the microstructure and mechanical behavior of the consolidates were examined and related to the processing route. Consolidated -325 mesh Cu powder exhibited a promising combination of high ultimate tensile stress (470 MPa) and ductility (20% tensile fracture strain). The near-perfect elastoplasticity exhibited by -325 mesh consolidate during tensile test was explained by a combined effect of strain hardening accommodated by large grains in the bimodal structure and softening caused by the recovery mechanisms such as trapping of dislocations at grain boundaries. Premature failure occurred during tensile loading in 130 nm consolidated powder, but the fracture strength was still 730 MPa for a fracture strain of 1.2%. Premature fracture is attributed to the remnant porosity because of the bimodal distribution of initial porosity. The present study shows that ECAE consolidation of nanoparticles opens a new possibility for the study of mechanical behavior of bulk nanocrystalline materials as well as offering a new class of bulk materials for practical engineering applications.
