Reinforcement with in-situ synthesized carbon nano-onions in aluminum composites fabricated by flake powder metallurgy

Bulk aluminum matrix composites reinforced with carbon nano-onions (CNOs) were fabricated by a flake powder metallurgy route. Homogenous dispersion of CNOs (with an average size of similar to 20 nm) was guaranteed by in situ polymer pyrolysis chemical vapor deposition of the precursor on Al nanoflakes with high specific surface area, followed by consolidating the CNO/Al nanoflake powders and then hot extrusion. The uniformly dispersed CNOs in ultrafine grained Al matrix exhibited remarkable strengthening efficiency: the 1.2 wt.% CNO/Al composite had a yield strength of 268 MPa and an ultimate tensile strength of 384 MPa, improved by 77% and 56% as compared to the Al matrix without CNOs, respectively. The strength enhancement with the in-situ CNOs is mainly attributed to a combined mechanism of grain boundary strengthening and Orowan strengthening. (C) 2015 Elsevier B.V. All rights reserved.