On the Damage Tolerance of Diffusion Bonded Titanium–Aluminum Phase Biomimetic Composites

ABSTRACT The biomimetic design principles of natural structures involve the strategic integration of stiff and compliant phases to synergistically enhance strength and toughness. Its evolutionary refined natural armor, characterized by a specialized microarchitecture, enables superior damage tolerance. However, achieving a continuous distribution of heterogeneous materials within metallic matrices remains challenging, particularly with respect to interface adhesion quality. Herein, diffusion bonding was employed to embed 6061 Al into additively manufactured Ti6Al4V scaffolds, yielding titanium–aluminum composites. A three‐dimensional interpenetrating network of composite constituents was achieved, with the pressure infiltration process yielding low porosity and facilitating the formation of intermetallic compounds at the interface. Spatially, the composites exhibited Bouligand, crossed‐lamellar, and spiral architectures. These biomimetic microstructures activated external toughening mechanisms, such as crack deflection and twisting, effectively redistributing stress, mitigating damage propagation, and suppressing crack growth. Consequently, the crack tip was shielded from applied stresses, resulting in enhanced fracture toughness and high damage tolerance. Furthermore, this approach markedly enhanced the tensile properties of the metal matrix composites with biomimetic architectures, achieving a strength‐to‐ductility balance comparable to that of conventional laminated composites.