Pore-gradient Ti6Al4V alloy mimicking the properties of human cortical bones: The design of TPMS structures by selective laser melting

The development of biomimetic pore-gradient materials has attracted considerable attention in the field of biomedical engineering, especially for applications in load-bearing implants. Ti6Al4V alloys are widely used in this context due to their biocompatibility and superior mechanical properties. However, to further enhance their functionality and integration with human tissues, it is crucial to develop materials that closely mimic the mechanical properties of human cortical bone. This study focuses on the design and fabrication of a pore-gradient Ti6Al4V alloy with versatile geometries of triply periodic minimal surface (TPMS) structures, produced via selective laser melting (SLM), to match the properties of human cortical bones. Structural analysis demonstrates precise control of the internal structure with pore sizes ranging from 250 to 745 mu m in absence of any defects. Through systematic analysis, we elucidate the significant influence of pore-gradient structures on the mechanical properties of TPMS structures in Ti6Al4V alloy. Notably, the mechanical properties, particularly the elastic modulus (16.8-25.7 GPa), compressive strength (185.7-462.3 MPa), and tensile strength (171.5-488.3 MPa), closely resemble those of human cortical bones. However, the pore-gradient TPMS structure exhibits nonuniform deformation due to the formation of crack branching in the internal structure. This research significantly contributes to the advancement of orthopedic implant technology by offering a promising avenue for the development of implants that closely replicate the biomechanical properties of natural bone, thereby mitigating stress-shielding effects and enhancing long-term implant stability.