ADVANCED β-TYPE TITANIUM ALLOYS AND MAO SURFACE FUNCTIONALIZATION FOR BIOMEDICAL APPLICATIONS

Titanium and its alloys are widely used in biomedical applications due to their excellent mechanical properties, corrosion resistance, and biocompatibility. However, conventional alloys such as Ti-6Al-4V exhibit limitations, including elastic modulus mismatch with bone and limited biological activity. β-type titanium alloys stabilized with non-toxic elements such as Nb and Mo have emerged as promising alternatives because of their lower elastic modulus and improved corrosion resistance. In addition, micro-arc oxidation (MAO) has been extensively investigated to enhance surface bioactivity and osseointegration. This study investigates the relationship between alloy microstructure and surface functionalization in titanium-based biomaterials. Metastable β-type titanium alloys were produced by arc melting under an inert atmosphere, followed by homogenization heat treatment. Microstructural characterization was performed using optical microscopy, SEM, EBSD, and TEM. Surface modification was carried out by MAO at 300 V for 3 min in an electrolyte containing calcium acetate, sodium glycerophosphate, and copper chloride, with current densities ranging from 1.0 to 2.5 A/cm². The resulting coatings were analyzed by XRD, XPS, and contact angle measurements. The alloys exhibited predominantly β-phase matrices with equiaxed grains and metastable features, including ω-phase formation and nanoscale heterogeneities associated with short-range ordering. These characteristics indicate that alloy composition and processing conditions strongly affect phase stability and may enable tailoring of elastic properties for improved mechanical compatibility with bone tissue. MAO-treated surfaces showed significant changes in morphology and chemistry depending on current density. Higher current densities promoted rutile TiO₂ formation, increased surface roughness, and enhanced hydrophilicity. XPS confirmed copper incorporation into the coatings, indicating potential antibacterial functionality. The results demonstrate that combining microstructural control with surface engineering provides a synergistic strategy to optimize both mechanical and biological performance. β-type titanium alloys functionalized by MAO coatings represent a promising approach for next-generation implants with improved osseointegration and long-term stability. (Financial support: CNPq and FAPESP).