Microstructure and mechanical properties of bioinspired laminated Al matrix hybrid reinforced with B4C and graphene nanoplatelets

Inspired by the hierarchical structure of the nacre shell and its related multi-scale strengthening and toughening mechanisms, B4C and graphene nanoplatelets (GNPs) hybrid reinforced laminated Al matrix composites were prepared via flake powder metallurgy. Compared with conventional B4C/Al composites with high B4C content, the laminated composites exhibit high relative density, strength and plasticity, and tensile elongation were all above 9.97%. The size of Al flakes obtained by ball milling is the key to realize the laminated structure. The Al flakes with large specific area provided larger contact area with reinforcements leading to low porosity. The large grain size was conducive to the movement of dislocations, while the nanocrystalline grains and interlayer interface hindered the movement of dislocations in the direction perpendicular to the laminates. The laminated structure and combination of hard reinforcement and soft phase Al matrix can achieve a good balance of strength and plasticity of the composites. The high strength reinforcements can effectively prevent crack propagation through the load transfer effect at the interface.