Bio-inspired muscle fascicle-like core–shell fiber bundle structure for enhanced toughness of Cf/Si3N4 composites

Modeling the microstructure of materials inspired by biomaterials opens up a proven route to making composites with higher toughness. Combined with the concept of bionics, this paper utilized a bio-inspired muscle fascicle-like fiber bundle structure to improve the toughness of C_f/Si₃N₄ composites. Li₂O-Al₂O₃-SiO₂ (LAS) was chosen as the raw material to grow SiC nanowires (SiCnw) in situ on the surface of carbon fibers. Subsequently, in the sintering process, the fibers were encapsulated with the Li-O-Al system to form a continuous nanolayer structure. Notably, the carbon fibers wrapped by the nanolayers formed a muscle fascicle-like fiber bundle structure. Compared with single fibers, the muscle fascicle-like structure has stronger toughness. When subjected to external forces, the strong toughness makes it less likely to break during the fracture process, resulting in a more pronounced pull-out. Muscle fascicle-like structures utilize this pull-out mechanism to absorb a large amount of fracture energy, resulting in a 24.5% increase in fracture toughness and a 98.4% improvement in work of fracture. This suggests that connecting the fibers into a fiber bundle structure through the intermediate phase can effectively exert the energy absorption mechanism, which provides a new idea to improve the mechanical properties of fiber-toughened composites.