Characterization of Ti-15Mo beta titanium alloy [orthopedic implants]

Beta titanium alloys are capable of providing a lower modulus of elasticity, enhanced corrosion resistance, improved fabrication response, and acceptable biocompatibility when compared to established titanium alloys. Small diameter Ti-15Mo bar product was solution treated at 800°C and rapidly quenched to produce a fine grained β microstructure at room temperature. Comparisons of microstructure, mechanical properties, corrosion, and biocompatibility were made to Ti Grade 4, Ti-6Al-7Nb, Ti-6Al-4V, and 316L stainless steel. ASTM grain size, inclusion content, and primary plus secondary phases were determined using optical microscopy. Smooth and notch tensile results were compiled and corrosion evaluation by anodic polarization was performed in nitrogen purged Ringer´s solution at 37°C. Biocompatibility testing included short term animal screening according to ASTM F 1408, cytotoxicity assays, and two year implantation in dogs. Molybdenum sensitization data were also documented. Overall results revealed a fine grain β microstructure, excellent corrosion resistance, tensile strength equivalent to Grade 4 Ti, lower tensile strength compared to the other alloys, but superior notch tensile properties of Ti-15Mo. Biocompatibility evaluations suggested a satisfactory level of localized biological response