Superior mechanical properties of interpenetrating phase composites integrating 3D-printed metal microlattice and infiltrating epoxy

The synergistic optimization of strength and toughness remains a critical challenge for mechanical metamaterials. To address this, this study aimed to investigate the interpenetrating phase composite (IPC) integrating metal-enhanced phase and epoxy-infiltrated phase with the hope to achieve superior strength-toughness properties. Truss microlattices and IPC specimens with conventional, reinforced, and hierarchical architectures were fabricated using selective laser melting and epoxy infiltration techniques. Experimental results show that the IPC metamaterials exhibited progressive large-deformation collapse sequences, mitigating the catastrophic collapse observed in pure truss microlattices. The IPCs demonstrated a synergistic enhancement (1 + 1 >2), with compressive strength exceeding the linear summation of constituent phases by up to 47.93% and specific energy absorption improved by 153.54% compared to pure truss microlattices. These improvements stem from interfacial interactions between the metal and epoxy phases, which enhance compressive strength during initial deformation, and achieve mutual crushing-supporting mechanism that promotes stable deformation in later stages. This study highlights significant performance enhancements in IPCs and offers insights into designing high strength-toughness metamaterials.