Characterization of ASTM F2066 Grade Alpha Plus Beta Ti-15Molybdenum

Titanium and its alloys are used as biomaterials due to their excellent biocompatibility, corrosion resistance, mechanical properties, metallurgical properties, and corrosion fatigue characteristics. Recently, there has been much interest in and development activity with several different metallurgical conditions of a, b, and a plus b titanium alloys for possible use as high strength biomaterials. One recent alloy development is Ti-15Molybdenum annealed and aged in the a plus b condition. This alloy is included in the 2008 revision of ASTM F2066, and has the same chemical composition limits as b annealed Ti-15Molybdenum. In a recent study conducted at the University of Mississippi Medical Center, a plus b Ti-15Mo showed greater smooth and notched mechanical properties (UTS, YS, Hv, and NTS) than CPTi Grade 4 cold-worked, annealed Ti-6Al-4V ELI, and annealed b Ti-15Mo. The ductile properties (Reduction of Area and % Elongation) of a plus b Ti-15Mo were lower than b Ti-15Mo, but were greater than CPTi Grade 4 cold-worked, and annealed Ti-6Al-4V ELI. Corrosion properties of a plus b Ti-15Mo were found to be equivalent to all of these other titanium alloys that were evaluated. Stress corrosion cracking failure mechanisms were not observed in either smooth or notched configurations of a plus b Ti-15Mo tested in distilled de-ionized water and Ringer's solution at 37¢ªC. Corrosion fatigue properties for a plus b Ti-15Mo were found to be greater at all levels on the S/N curves compared with the other titanium alloys evaluated for both smooth and notched configurations. The fatigue notch sensitivity for a plus b Ti-15Mo was found to be less than Ti-6Al-4V ELI, equivalent to CPTI Grade 4 (cold-worked), and greater than b Ti-15Mo. Results indicate that a plus b Ti-15Mo exhibits physical, mechanical, and electrochemical properties which make its use for high strength implant applications a definite possibility.