Effect of a novel sintering technique: hot coining on microstructure and mechanical properties of MWCNT reinforced Al metal matrix nanocomposite

Abstract

ABSTRACT Fabrication of MWCNT-reinforced nanocomposites with uniform distribution is still remaining as a challenge. Even for researchers who achieved uniform distribution in powder, boundary agglomerations are observed after sintering. Hot coining (HC) a novel technique for bulk sampling can achieve uniform distribution during sintering. Several mechanical testing and characterisation methods are applied closely to explore the mechanical properties and structural features of the hot coined AA2219-MWCNT composites. Hot coining results in significant improvement of mechanical properties when reinforced with 0.75 wt.% MWCNT shows 38.8 % (Rockwell hardness), 106% (UTS), 183 % (impact strength) and 76% (radial crushing strength). But retardation in mechanical properties was observed above 0.75 wt. %. During HC particle rearrangement and pushing of MWCNT towards particle boundary is not taking place as in other conventional and advanced sintering technology. The fracture surface of HC tensile specimen shows uniform dispersion and MWCNT alignment in the matrix. The fracture surface shows the mixed mode of fracture (ductile-brittle), and ductility is found to be decreasing with increased MWCNT concentration.