Microstructure and mechanical properties of Ti-35Nb-6Ta alloy after thermomechanical treatment

The influence of thermo-mechanical treatment on microstructure and mechanical properties of T-35Nb-6Ta has been studied. The thermo-mechanical treatment was chosen to correspond to the production of wire with suitable mechanical properties for dental implants. After casting the alloy was hot forged (700–900 °C), solution treated (850 °C/30 min, water quenched) and cold swaged (reductions up to 91%). The annealing (700 °C/3 h/furnace) or aging (450 °C/8 h/furnace) was used as final heat treatment. The microstructure was studied by using light microscopy, scanning electron microscopy, transmission electron microscopy and XRD analysis. Cold swaging introduces microstructure consisting of highly deformed β-phase grains with dislocation tangles and twins, which ensures high tensile strength about 820 MPa, low Youngʹs modulus (~ 50 GPa) and good ductility ~ 10%. Subsequent aging increases tensile strength (1000 MPa) as well as Youngʹs modulus (75 GPa) without diminishing ductility. Annealing at 700 °C slightly decreases tensile strength (730 MPa) and increases the ductility and Youngʹs modulus (17% and 62 GPa respectively). The mechanical properties attained recommend the thermo-mechanical treatment for production of wires for dental implants.