Bioinspired micro-nano laminated Nb/Nb5Si3 composites fabricated by high-energy ball milling and spark plasma sintering

This study proposes a novel strategy to overcome the strength-toughness trade-off in Nb/Nb₅Si₃ composites by designing bioinspired micro-nano laminated architectures similar to a “brick-and-mortar” structure. Utilizing the novel approach developed in this study, the bioinspired micro-nano laminated Nb/Nb₅Si₃ composites were successfully fabricated. This architecture enables Nb/Nb₅Si₃ composites to possess an excellent combination of toughness and strength to exceed the mechanical properties of previously reported Nb-Si composites and overcome the conventional strength-toughness trade-off. The excellent mechanical properties may be attributed to dislocation bowing movement and deformation twinning. Dislocation bowing facilitates long-range stress dissipation and reduces local stress concentration to enhance strength and toughness. The deformation twinning can consume stress to improve strength and toughness. The micro-nano laminated architecture promotes the formation of tearing ridges that exhibit the same alignment as the laminated structure. The formation of tearing ridges increases energy dissipation during crack propagation and deflects the crack path to extend the propagation distance, ultimately improving fracture toughness.