Effects of ceramic lamellae compactness and interfacial reaction on the mechanical properties of nacre-inspired Al/Al2O3-ZrO2 composites

Freeze casting has been proven to be a versatile processing approach for the design of biomimetic composites that exhibit unique combinations of strength and toughness. However, to date, most studies have focused on polymer-ceramic composites, and very limited work has examined metal-ceramic composites, even though the latter possess much superior mechanical properties. In this work, we prepared nacre-like Al/Al2O3-ZrO2 composites using freeze casting and pressure infiltration techniques and then investigated the influences of the ceramic lamellae compactness and interface reaction on the mechanical properties and fracture behavior of the composites. The results show that the compactness of the ceramic lamellae greatly influences the Al penetration and subsequent interfacial reaction with ZrO2. The presence of Al3Zr reaction product layers facilitates crack initiation and interface debonding, weakening the fracture toughness of the composites. The ceramic lamellae can be densified by using fine ceramic particles and increasing the ceramic loading and sintering temperature, thus greatly reducing the extent of the interfacial reaction and improving the strength and toughness of the materials.