Microstructure-based modeling on structure-mechanical property relationships in carbon nanotube/aluminum composites

The present work investigates structure-mechanical property correlations of carbon nanotube/aluminum (CNT/Al) composites through characterization and microstructure-based modeling. The nanoscale architecture of these composites, produced by flake powder metallurgy, was established using a transmission electron microscope equipped with an automated crystal orientation mapping system. The architecture mainly consists of elongated Al grains with sub micron widths and micron lengths, intergranular CNTs and an interfacial reaction product, namely Al4C3 particles. The stress-strain behavior found with our dislocation-boundary/reinforcement interaction mechanical model, matched our experimental tensile curves. This model was also used to predict several key factors, namely grain dimensions, CNTs volume fraction, intergranular or intragranular distribution and aspect ratio, interfacial reaction rate, impacting tensile strength and ductility. It was found that intergranular CNTs induced strengthening will not result in lower uniform elongations, while intragranular distribution of low aspect ratio CNTs and Al4C3 nanoparticles can increase both strength and uniform elongations by the Orowan mechanism. It is expected that the model in the present work can assist in microstructure design of metal matrix nanocomposites.