Bioinspired tough and strong ZrB₂-SiC_w/Ti–Nb–Ti hybrid composites with a hierarchical ceramic-metal architecture

Triple-layered Ti–Nb–Ti foils were introduced into ZrB₂-based ceramics to form heterogeneous ceramic–metal layered composites. Following spark plasma sintering and mechanical processing, the fracture toughness of laminated ZrB₂-SiC_w/Ti–Nb–Ti ceramics (15.18 MPa m^1/2) was significantly improved in comparasion to monolithic ZrB₂-SiC_w ceramics (7.33 MPa m^1/2). In situ formation of TiB₂ and (Ti, Nb)C whiskers alleviated interfacial residual stress and improved interfacial bonding strength. Plastic deformation (such as slip, dimple, and tear-ridge) arising from the existence of a ductile Ti–Nb solid solution ((Ti, Nb)_ss), Ti, and Nb was observed in the fracture surface of the interlayer, leading to the improvement of toughness. Moreover, an increase in R-curve behavior indicated a lower sensitivity to cracks in ceramics with metallic interlayers compared to monolithic ceramics.