Nacre‐like ceramic–metal composites: State‐of‐the‐art, challenges, and opportunities

Abstract Nacre's unique brick‐and‐mortar microstructure, composed of aragonite platelets bonded by biopolymers, serves as a source of inspiration for designing composites with combined strength and toughness. By replicating nacre's microstructure, researchers have developed nacre‐like (NL) ceramic–metal (CM) composites with superior mechanical performance and functionalities, enabling diverse applications. This review critically examines the recent advancements in NL CM composites, emphasizing their mechanical and functional properties, including strength, toughness, hardness, wear resistance, lightweight design, and electrical and thermal conductivity. The fabrication processes are categorized into two primary routes, detailing the specific microstructures that result and assessing the advantages, limitations, and alternatives associated with each process. Comparative analyses of flexural strength and fracture toughness across various NL CM composites, based on ceramic–metal combinations and ceramic volume fractions, are presented, along with discussions of specific strength and specific fracture toughness. Deviations in mechanical properties relative to the rule of mixtures are highlighted, with explanations for observed enhancements or reductions. This review highlights that good interfacial bonding between the ceramics and the metals can significantly enhance the strength and toughness of NL CM composites even at lower ceramic volume fractions. This review also explores the multifunctional attributes of some NL CM composites, concluding with an outlook on the challenges, future opportunities, and potential applications of NL CM composites in advanced material engineering.