High damage-tolerance nacre-inspired TiB2/Al-Cu composites with adjustable mechanical performance based on heat-treatment condition tuning

Abstract

High damage-tolerance nacre-inspired TiB2/Al-Cu composites are successfully prepared by freeze casting and pressure infiltration. The obtained composites have a great application potential as lightweight structural components due to their high strength and toughness. The microstructure and mechanical properties of the nacre-inspired TiB2/Al-Cu composites are characterized, and their fracture and toughening mechanisms are also investigated. The results show that both the as-cast and heat-treated TiB2/Al-Cu composites possess excellent mechanical properties, which can be attributed to several toughening mechanisms, including the passivation, branching, deflection, and bridging of cracks. These are due to the Al phases in the ceramic layers, as well as the plastic deformation of the Al-Cu layers and the interconnected network structure. The heat treatment can significantly improve both the strength and toughness, which can be attributed to the decrease of the crack propagation possibility resulted by the decrease in the Al2Cu content after heat treatment, as well as the existence of metal bridges and the pull-out behavior resulted by the high plasticity of the Al matrix. This study demonstrates that mechanical properties of high damage-tolerance nacre-inspired TiB2/Al-Cu composites can be controlled by tuning the heat-treated conditions, which can be beneficial to the industrial application of such composites in the manufacturing of components such as brake discs and protective armors.