Surface anodization of the biphasic Ti13Nb13Zr biocompatible alloy: Influence of phases on the formation of TiO2 nanostructures

• Published in: Journal of alloys and compounds 2019-08, Vol.796, p.93-102
• Main Authors: Pérez, Diego Alfonso Godoy, Jorge Junior, Alberto Moreira, Asato, Gabriel Hitoshi, Lepretre, Jean-Claude, Roche, Virginie, Bolfarini, Claudemiro, Botta, Walter Jose
• Format: Article
• Language: English
• Subjects: Anatase; Anodization; Anodizing; Beta phase; Biocompatibility; Chemical Sciences; Corrosion; Corrosion resistance; Deformation; Heat treatment; Nanostructure; Nanotubes; Nonaqueous electrolytes; Pitting (corrosion); Porosity; Surface modification; Ti13Nb-13Zr alloy; TiO2 nanopores; TiO2 nanotubes; Titanium base alloys; Titanium dioxide
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.04.167

Here we report for the first time that the anodization of the biphasic (α'+β) Ti13Nb13Zr alloy form arrays of TiO2 nanotubes with well-defined circular geometry in the α′ phase, while nanopores of TiO2 are formed in the β phase. Samples of the Ti13Nb13Zr alloy were severely plastic deformed using High-Pressure Torsion (HPT) to refine the microstructure and to redistribute α′ and β phases. The anodization was performed using an organic electrolyte (glycerol) containing fluoride ions and a few percentages of water. All the specimens coated with nanotubes were annealed at 550 °C to crystallize the modified surface of the as-anodized samples. XRD analyses confirmed that the as-anodized amorphous nanostructures crystallize in a mixture of anatase and rutile after heat treatment, and SEM observations showed no significant morphological changes in the surface phases. The evaluation of corrosion resistance showed that anodized samples have much better corrosion properties than polished ones without any evidence of pitting corrosion. Quantitative comparison between anodized coarse-grained (α'+β)-Ti alloy and ultra-fine grained (α'+β)-Ti one showed that the nanostructuring of the (α'+β)-Ti alloy by HPT helped to improve the bioactivity when compared with the coarse-grained sample. [Display omitted] •Ti-13Nb-13Zr (α'+β) alloy was processed by High-Pressure Torsion.•Anodization of deformed and un-deformed form arrays of nanotubes in α′-phase.•Anodization of deformed and un-deformed form nanopores in β-phase.•Deformed or not, anodized samples have much better corrosion properties.•Bioactivity of anodized (α'+β)-Ti alloys is reduced compared to cp α-Ti.