Nanostructure formation on Ti-Nb alloys promote better surface properties designed for biological applications

Anodizing was employed to produce organized TiO₂ nanotubular structures (NTs) on two titanium alloys : Ti-15Nb (TN15), which exhibits both bcc and hcp crystal structures (α′ + β phases), and Ti-40Nb (TN40), characterized by a stable β phase. The electrochemical treatment was conducted under different potentials (10 V and 20 V) and durations (1 h and 2 h). Following anodization , samples underwent thermal treatment to transform the initially amorphous NT layers into crystalline phases . X-ray diffraction (XRD) confirmed the amorphous nature of the as-anodized surfaces, which crystallized into anatase and rutile phases after heating. Structural and microstructural features were analyzed via XRD, scanning electron microscopy (SEM), and atomic force microscopy (AFM), which were used to assess surface roughness, NT length, and diameter. Wettability and surface free energy were evaluated using the sessile drop contact angle method. This study investigates how anodization parameters and alloy composition affect the crystallinity , morphology, and surface properties of TiO₂ NTs. TN15 samples exhibited α-phase Ti with a mix of anatase and rutile, while TN40 samples showed dominant β-phase Ti and greater rutile content. NTs on TN15 were more uniformly aligned, whereas TN40 formed NTs in isolated domains. Longer anodization times and higher voltages increased NT length and diameter. Notably, surface wettability improved with greater anatase content—particularly in TN15–2h-10V (contact angle ∼7°)—highlighting the influence of Nb content, anodization conditions, and heat treatment on tuning NT functionality for biomedical applications .