Strong and tough bioinspired nacre-like B4C/Al functionally graded materials with eliminated abrupt interfaces

Due to multiple length-scale and gradient microstructures, numerous living organisms have optimized performance. Herein, inspired by the gradient structure of nacre, biomimetic materials with gradient microstructure were attempted to be created via overcoming the challenges of limited methods. The combination of layer-by-layer casting and gelation-freeze-drying were firstly used to produce ceramic scaffolds with continuously graded channels, followed by infiltrating molten alloy into the scaffolds, new B4C/2024Al bi-continuously functionally graded materials (FGMs) equipped with nacre-like and multicomponent gradient structures were developed. Since continuous ice crystals grew across the interface between layers and the around ceramic particles were rearranged during the solidification of the layered wet suspension, abrupt interfaces between layers were effectively eliminated in the scaffolds and final FGMs. Importantly, these unique structures not only provide an exceptional combination of strength and toughness but also allow for a smooth transition of properties. Our feasible approach paves a novel avenue to create FGMs in terms of biomimetic structures with high-performance. [Display omitted] •The porous B4C scaffolds with continuously graded channels are produced by layer-by-layer casting and gelation-freeze-dry processes.•New B4C/2024Al bi-continuously FGMs effectively eliminate delamination and abrupt changes between layers.•These composites provide an exceptional combination of strength and toughness.