Biomimetic Design and Mechanical Properties of Additively Manufactured Titanium Alloy Implant with Gradient Gyroid Structure.

Titanium alloy bone scaffolds have been widely used in the clinical treatment of bone defects. However, conventional titanium alloy bone scaffolds exhibit a lack of porous structure and excessively high elastic modulus, resulting in poor osseointegration. In this study, mimicking the structural characteristics of human bone-namely dense exterior and porous interior-three types of bionic Gyroid titanium alloy bone scaffolds with a uniform porosity of 50% but distinct gradient properties were designed, including uniform lattice structure, linear gradient structure, and quadratic gradient structure. Process optimization of selective laser melting (SLM) and characterization of the as-fabricated microstructures were carried out. The tensile and compressive properties of additively manufactured titanium alloy bone scaffolds were investigated via mechanical testing and finite element analysis (FEA). The results demonstrate that optimized SLM parameters yield a matrix relative density of 98.56% for solid Ti-6Al-4V reference specimens. Using these parameters, bionic gradient-porosity Gyroid bone scaffolds were successfully manufactured. The bionic quadratic function gradient design achieves optimal modulus matching (10-30 GPa) and sufficient mechanical strength at the design level, satisfying the mechanical requirements for bone scaffolds and showing favorable application potential for load-bearing bone scaffolds.