Periodic and aperiodic Ti lattices additively manufactured under reactive atmosphere: Mechanical and biological properties

Porous Ti materials can reduce the so-called stress shielding effect and are widely regarded as superior biomedical materials. In this study, commercially-pure Ti (CP-Ti) with five different porous structures, namely Dodecahedron, Diamond, Gyroid, Fischer Koch S, and Voronoi, have been printed using Powder Bed Fusion Laser Beam (PBF-LM) and under a reactive atmosphere (97%Ar+3%N-2). Compressive tests and in vitro bio tests including osteogenic mineralization and cytotoxicity have been conducted to evaluate their mechanical and biomedical performances. Analytical means such as laser confocal microscopy have been used and radar properties maps have been built to compare overall properties of these different lattices. Results show that some of the porous CP-Ti lattices (with Gyroid and Fischer Koch S arrangement) can achieve engineering fracture strength above 1000 MPa, while maintaining their low Young's modulus (<20 GPa) and good biocompatibility. For the lattices, relationships between Young's modulus and relative density are discussed under the scheme of the Gibson and Ashby model (G-A model) with C constant as 0.1-4. Energy absorption data for the lattices are provided, showing high values due to the excellent combination of strength and ductility. The study implies that a good selection of the lattice type together with the approach of printing under reactive atmosphere can lead to advanced Ti lattices for biomedical applications.