Ti-PEEK Interpenetrating Phase Composites with Minimal Surface for Property Enhancement of Orthopedic Implants

Bioinspired interpenetrating phase composites (IPCs) present a promising strategy for augmenting the mechanical properties of materials, thereby synergistically enhancing the strength and fracture toughness of orthopedic implants. In this study, Ti6Al4V-PEEK IPCs were fabricated by pressing molten PEEK into additively manufactured Ti6Al4V scaffolds designed using minimal surface structures. The mutual spatial interpenetration and strong binding between Ti and PEEK were confirmed through CT detection and SEM analyses, revealing the presence of continuous constituents within biomimetic architectures. Due to interpenetration promoting interaction and efficient stress transfer of the two phases, IPCs enhances toughness and energy absorption by over 291% and 309% respectively while maintaining bone-compatible elastic modulus and higher strength. The mechanisms underlying stress dispersion, crack propagation resistance, and prolonged stress plateau period of IPCs were investigated through the utilization of digital image correlation (DIC) and finite element simulation techniques. Among the various types of IPCs investigated, Gyroid IPCs exhibit superior comprehensive mechanical properties, thereby facilitating the development of customized IPCs aimed at ensuring long-term stability in orthopedic implantation scenarios.