Heat treatment processes and mechanical properties of new β-type biomedical Ti-29Nb-13Ta-4.6Zr alloy

Practical size ingot of new β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr, which was composed of non-toxic elements of Nb, Ta and Zr, with lower modulus of elasticity, high strength and excellent biocompatibility was tried to be fabricated. Then the heat treatment processes of the alloy, which gave a good balance of strength, ductility and modulus of elasticity, were investigated in this study. Practical size ingot of Ti-29Nb-13Ta-4.6Zr with a weight of 17 kg has been successfully fabricated. The distribution of alloying elements was homogeneous through the ingot. The practical size ingot can be easily hot forged and cold rolled by a total reduction of 98%. Ti-29Nb-13Ta-4.6Zr which was aged after cold rolling indicates higher strength and lower elongation as compared with those of the alloy aged after solution treatment. In the aging temperature range between 598 K and 648 K, the alloy indicates relatively higher strength and lower elongation. The precipitation of ω phase increases tensile strength and decreases elongation in the alloy aged between 598 K and 643 K after solution treatment. In the aging temperature above 673 K, the precipitation of α phase increases tensile strength and elongation in the alloy aged after solution treatment. New alloy has excellent strength ductility relationship when aging temperature was above 673 K.