Synergistic Optimization of Mechanical and Biological Properties in LPBF-Fabricated Porous Ti6Al4V Scaffolds via Structural Design and Surface Modification

Porous Ti6Al4V scaffolds with tailored architectures are promising candidates for orthopedic implants due to their potential to mitigate stress shielding and enhance osseointegration. In this study, porous Ti6Al4V scaffolds with different unit cell geometries and porosities were fabricated via laser powder bed fusion (LPBF). The effects of pore structure and porosity on mechanical and biological properties were systematically investigated. The results show that both elastic modulus and compressive strength decrease with increasing porosity, and a critical porosity of 70% is identified for uniform structures, beyond which their load-bearing capacity becomes insufficient; however, a radial gradient design can overcome this limitation. Alkali heat treatment generates a uniform sodium titanate nanowire coating, which significantly improves wear resistance and promotes apatite deposition, thereby enhancing bioactivity. Among all samples, the hexagonal diamond structure with 70% porosity exhibits the highest cell viability. To overcome the trade-off between mechanical strength and biological performance inherent in uniform porous structures, a radial gradient porous scaffold with an average porosity of 72.5% was designed. The gradient structure demonstrates improved mechanical strength while maintaining high bioactivity, indicating its potential for optimized orthopedic implant applications.