Gaining strength-ductility combination in Al matrix composites with in-situ synthesized three-dimensional nanocarbon network

Abstract

As a promising architecture reinforcement, the three-dimensional (3D) configuration of nanocarbon holds great prospects in achieving a strength-ductility combination for metal matrix composite (MMCs). However, due to the native deficiency of Al in catalyzing the growth of nanocarbon, constructing a nanocarbon network has been the long-term challenge for Al matrix composites (AMCs). Herein, we develop a new strategy for synthesizing AMCs reinforced by three-dimensional nanocarbon (3D-C) via plasma-enhanced chemical vapor deposition (PECVD) integrated with hot pressing (HP) as well as hot extrusion, demonstrating exceptional mechanical properties. The detailed characterization reveals that the in-situ generation of nanocarbon layers on the surface of Al powders is attributed to the initiation of isolated carbon islands, followed by merging and self-assembly, which is governed by the PECVD-assisted catalysis growth-regime. The subsequent welding of nanocarbon layers during the HP promotes the formation of interlocking 3D-C networks in Al matrix, enhancing the sintered densification of the composite. Such unique nanocarbon distribution configuration not only effectively constrains the coarsening and deformation of Al grains, but also notably accumulates dislocation under high stress conditions. Moreover, 3D-C with a strong interfacial bonding contributes to the toughness through the microcracks, bridging cracks as well deflecting cracks, which accounts for the high toughness of the composite. This work provides new insights into the 3D distribution configuration of reinforcements in AMCs to achieve the optimized mechanical performance of composites.