A 3D interconnected CNT-RGO hybrid networks for Al matrix composites: Unveiling a new pathway to superior strength-ductility balance

Abstract

Achieving a balance between strength and ductility in Al matrix composites (AMCs) remains a persistent challenge due to issues such as agglomeration of reinforcements and weak interfacial bonding. This study addresses these limitations by incorporating a 1.5 wt% hybrid nanocarbon reinforcement consisting of carbon nanotubes (CNTs) and reduced graphene oxide (RGO) into an Al matrix, denoted as (CNT-RGO)1.5 wt%/Al, using a flake design strategy. A systematic flake dispersion process, combining low-speed ball milling (BM), aqueous PVA-assisted slurry mixing, and extrusion, is employed to achieve a uniform distribution of CNT-RGO hybrids forming a robust, interconnected 3D network. The hybrid reinforcement enhances load transfer via mechanical anchoring by CNTs and planar bridging by RGO sheets, significantly improving interfacial bonding. Microstructural analysis reveals refined grains (∼550 nm), high dislocation density (∼7.4 × 10¹⁴ m⁻²), and a moderate Al₄C₃ content (∼1.62 %), all contributing to the observed properties. As a result, the (CNT-RGO)/Al composite exhibits a superior balance between tensile strength (460 ± 7 MPa) and fracture elongation (31.6 ± 3 %), outperforming single-reinforced counterparts and unreinforced Al by ∼165 % in strength and ∼19 % in ductility. Finite element simulations confirm the effectiveness of the 3D hybrid network in load transfer and mechanical enhancement. This study demonstrates the importance of hybrid reinforcement configuration to almost fully utilize the superior properties of different reinforcements and provides a cost-effective and feasible approach for the development of next generation high-performance AMCs.