TiO₂ Nanotube-Based Surface Modification of EB-PBF Ti6Al4V: Toward Multifunctional Performance Enhancement

The surface modification and anodization behavior of Ti6Al4V (Ti64) alloy components produced by electron beam powder bed fusion (EB-PBF) were investigated to enhance their compatibility for biomedical applications. Ti64 samples were fabricated using optimized EB-PBF parameters to achieve a uniform microstructure and surface finish. Anodization was performed at 40 V and 60 V, resulting in the formation of self-organized TiO₂ nanotube arrays. Subsequently, a heat treatment at 550 °C was applied to improve the crystallinity of the nanotubes while preserving their structural integrity. Surface morphology and topography were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM), revealing voltage-dependent variations in nanotube thickness and surface roughness. Phase composition analysis using X-ray diffraction (XRD) confirmed the formation of anatase TiO₂. Mechanical properties were evaluated using nanoindentation and nanoscratch techniques, showing higher hardness and improved adhesion in samples anodized at 40 V, attributed to their denser nanotube structure. Electrochemical testing demonstrated a significant enhancement in corrosion resistance in anodized samples compared to their untreated parts. Furthermore, in vitro bioactivity analysis confirmed increased apatite formation on anodized surfaces, indicating an improved biological response. These findings demonstrate that the combination of EB-PBF and controlled anodization presents an exciting approach for modifying the surface properties of Ti64 parts, thus improving their mechanical performance, corrosion resistance, and bioactivity for biomedical applications.