Fabrication and characterization of a high strength ultra-fine grained metal-matrix AA8006-B4C layered nanocomposite by a novel accumulative fold-forging (AFF) process

In this study, a new manufacturing process, accumulative fold-forging (AFF), based on the severe plastic deformation (SPD) concept was implemented for fabrication of nanostructured metal-matrix nanocomposites. This process was accomplished at room temperature for up to 26 fold-forging steps with an intermediate annealing treatment at a temperature of 150 degrees C between the passes, and produces 67,108,864 layers to incorporate a similar to 10 vol% of boron carbide nanoparticles homogenously within the Al-Fe-Mn aluminum alloy matrix. The results indicate a structure is formed with well-bonded interfaces/inter-layers with uniformly dispersed precipitates and nanoparticles between them, leading to formation of an ultra-fine grain structure in the matrix with a mean grain size <50 nm and a dislocation density as high as similar to 8.1 * 10(16) m(-2). As a result, an ultra-fine grained (similar to 35 nm) AA8006-B4C (34 nm, 10 vol%) layered metal-matrix nanocomposite was produced. The hardness of annealed Al-foil was similar to 30HV which was enhanced by more than six times to a maximum amount of similar to 205.4HV, corresponding to one of the highest reported hardness values for an aluminum based composite, due to the role of nanolayers, nano-grains, and nano-particles as the main strengthening mechanisms. (C) 2018 Elsevier Ltd. All rights reserved.