Fabrication and characterization of alumina-copper composites with complex bioinspired microstructures

Natural organisms are a rich source of inspiration for designing bioinspired microstructures that can be integrated into composites to achieve tunable mechanical performance. However, the inclusion of such structural motifs has been limited to a few structures only due to processing limitations, but the current advancements in composite manufacturing such as magnetically assisted slip casting in conjunction with pressureless sintering have enabled the precise creation of complex microstructures in ceramic-metal (CM) composites. Here, we produced bioinspired Al₂O₃-Cu composites with five distinct microstructures including brick-and-mortar, cross-lamellar, herringbone, Bouligand and functionally graded microstructure, inspired from molluscs, conch shells, impact and periodic regions of mantis shrimp's dactyl club and a combination of crab and molluscs, respectively. The responses of these composites are systemically investigated under different loading conditions. It was found that the brick-and-mortar microstructured and herringbone microstructured CM composites exhibited the highest flexural and compressive strengths, whereas the Bouligand microstructured composites demonstrated the greatest crack growth toughness. The zigzag arrangement in the herringbone microstructured CM composites achieved the highest energy dissipation by damping, while the Bouligand and the cross-lamellar microstructured composites exhibited the lowest damping response but the highest energy absorption during impact due to their twisted microstructures. These findings provide valuable insights into the structure-property correlations in bioinspired CM composites and establish a framework for tailoring mechanical performance through controlled microstructural design.