Bioinspired metal infiltration strategy for near-net-shape ceramic-metal heterogeneous composites

Ceramic materials are valued in aerospace, automotive, and protective applications for their high-temperature stability, corrosion resistance, and hardness, but their inherent brittleness limits simultaneous improvement of strength and toughness. Inspired by natural architectures, a fabrication strategy integrating material extrusion, ultrasonic-vacuum-assisted cyclic metal infiltration, and stepwise vacuum heat treatment is proposed for ceramic-metal composites. Microstructural and phase analyses indicate that the metallic phase effectively infiltrates the porous ceramic scaffold and forms stable interfaces. Mechanical tests show that the composites with optimized heat treatment and about 4.6 wt% metal content exhibit increases of 482.5% and 727.5% in compressive strength and energy absorption, respectively, compared to the matrix without metal infiltration, displaying a notable synergistic effect of strength and toughness. Multiscale simulations further reveal that the biomimetic structure establishes continuous heterogeneous load-transfer pathways that homogenize stress distribution, while the metallic phase buffers stress and dissipates plastic deformation energy. Metal filling fraction studies indicate that mechanical performance is governed by the coupled effects of ceramic rigidity and metallic plasticity. The approach is further extended to the Al 2 O 3 /IN718 system, confirming its versatility and scalability. Overall, this work presents a biomimetic multiscale design strategy for constructing lightweight ceramic-metal composites with enhanced mechanical performance.