Dimensionally hybrid architecture-property relations in carbon nanotubes and silicon carbide nanoparticles reinforced aluminum matrix composites

Achieving an optimal strength-ductility synergy in aluminum matrix composites (AMCs) requires intelligent architectural design of multi-dimensional reinforcements. This study focuses on distinctive dimensional characteristics of hybrid reinforcements, combining one-dimensional multi-walled carbon nanotubes (1D CNTs) with zero-dimensional silicon carbide nanoparticles (0D SiCnp) in 6013Al matrix. By fixing volume ratio at 1:1 and varying total reinforcement content from 2 to 8 vol%, we systematically elucidate how the interplay between 1D and 0D reinforcements governs microstructural evolution and mechanical responses. The composite with 2 vol% CNTs and 2 vol% SiCnp exhibits the most balanced performance, delivering a tensile strength of 662 MPa and an elongation of 8.6%. This optimum is attributed to a spatially partitioned architecture wherein over 50% of reinforcements are encapsulated within Al grains, enabling efficient Orowan looping, load transfer and dislocation storage. Beyond this threshold, severe agglomeration redistributes reinforcements to grain boundaries, transforming them into stress concentrators and degrading both strength and ductility. Quantitative analysis confirms that the deterioration of reinforcement-related strengthening outweighs the continued benefits of grain refinement and geometrically necessary dislocations. This work emphasizes that preserving uniform dispersion and dimensional complementarity is key to harnessing the potential of hybrid nanocomposites, providing a microstructure-guided design principle for high-performance AMCs.