Enhancing strength and toughness of GNS/Al nanocomposites via a hybridization strategy

Abstract

Good strength-ductility balance in graphene nanosheet (GNS)-reinforced aluminum nanocomposites can be achieved through tailorable and facile agglomeration control. Our previous study showed that pre-modulating the Al powder morphology by adding hard silicon carbide nanoparticles (SiCnp) during the two-step ball milling process effectively promotes the uniform dispersion of GNSs. However, excess SiCnp content causes SiCnp aggregate and premature cracking of composites. Here, GNS-reinforced aluminum nanocomposites with different SiCnp content (0.3–1.5 vol%) were prepared, and the optimal SiCnp-to-GNS ratio was determined after optimizing the SiCnp content in a pre-studied composite preparation process. The effect of SiCnp on the microstructure and mechanical properties of the composites was systematically investigated. The cold welding deformation of Al flakes increased with the SiCnp content. Nonetheless, inadequate or excessive SiC content caused insufficient lamination or excessive cold-weld stacking of Al flakes, respectively. Al-0.9vol.%SiCnp powders possessed the highest specific surface area which resulted in high homogeneous dispersion of 3.0 vol% GNS during the second ball-milling stage. Consequently, the resulting hybrid reinforced (GNS + SiCnp)/Al composites showed simultaneous improvement in strength and plasticity, unlike Al-3.0vol.%GNS composites. This showed that introducing hard nanoparticles (i.e., the hybridization strategy) is a promising method to simultaneously enhance strength and plasticity of aluminum nanocomposites.

Keywords

• Aluminum matrix nanocomposites
• Hybrid composites
• Hot extrusion
• Intra-crystalline nanoparticle distribution
• Strength and toughness