Tailoring performance of PBF-EB additively manufactured Ti-6Al-4V ELI alloy for biomedical use through surface pre-treatment and anodization

Powder Bed Fusion with an Electron Beam (PBF-EB) enables the fabrication of patient-specific titanium implants with complex geometries; however, the inherent roughness and unique surface features of PBF-EB-produced alloys complicate the optimization of both corrosion resistance and biological performance. This study investigates the combined effects of mechanical surface pre-treatment and anodic oxidation on PBF-EB-manufactured Ti-6Al-4V ELI. Raw, sandblasted, and machined substrates were anodized in orthophosphoric acid at 15 V and 30 V, and their surface topography, surface chemistry, electrochemical behaviour, early-stage bacterial adhesion, and osteoblast colonization were evaluated. Mechanical pre-treatment was found to define the primary surface topography, while anodization modified surface morphology and chemistry in a voltage- and surface-condition-dependent manner. X-ray photoelectron spectroscopy showed that titanium was present exclusively as Ti 4+ , consistent with fully oxidized TiO₂ at the investigated surfaces, while phosphate- and calcium-containing species were detected after anodization. Electrochemical testing indicated that corrosion behaviour depended on both the initial surface condition and anodizing voltage. Anodization at 30 V was associated with favourable electrochemical responses on machined and sandblasted surfaces but with reduced corrosion resistance on the highly rough as-built substrate. Qualitative and semi-quantitative analysis showed that bacterial fluorescence intensity varied between the investigated surface conditions and may be associated with both surface morphology and chemistry. The highest osteoblast-associated Neutral Red signals were observed for the anodized sandblasted surfaces. Overall, the results indicate that the response of PBF-EB-produced Ti-6Al-4V ELI to anodization depends on the initial surface condition. The combined analysis provides useful guidance for selecting surface preparation and anodization conditions for biomedical applications.