On structure and mechanics of biomimetic meta-biomaterials fabricated via metal additive manufacturing

Additively manufactured (AM) metamaterials with unparallel mechanical and biological properties have been of interest for many biomedical, aerospace, and defense applications. In this study, new findings on the structure-property relationships of a specific class of AM meta-biomaterials based on minimal surfaces which have not been well understood previously (i.e., Primitive and Schoen-IWP (IWP)) are presented. Biocompatible Ti-6Al-4V meta-biomaterials based on Primitive and IWP topologies, with three different morphological properties for each, were designed and fabricated via laser powder bed fusion technique. The microstructure, morphological, quasi-static compressive, flexural properties, and fracture mechanisms of the designed meta-biomaterials are thoroughly evaluated. Studied meta-biomaterials exhibited distinct fracture mechanisms under flexural loading depending on their topology; crack growth path was either zigzag (i.e., deflected) or straight. Additionally, Primitive meta-biomaterials exhibited ductile material behavior, under both compressive and flexural loading conditions, with pore size, porosity, and elastic gradient similar to the trabecular bone (850–1020 μm, 40–64%, and 3200–6000 MPa). However, IWP meta-biomaterials showed brittle behavior with porosity and elastic gradient closer to cortical bone (20–42% and 7000–13,000 MPa). These outcomes indicate that both mechanical behavior and fracture mechanisms of meta-biomaterials can be controlled based on topology and morphology.