Study on the mechanical property and microstructure of surgical implanted Ti-6Al-7Nb titanium alloy

Ti-6Al-7Nb titanium alloy is attractive to medical device industry for orthopedic applications, such as total hip replacement systems, fracture fixation plates, intermedullary rods and nails, spinal devices, screws, and wires. Substituting Niobium for Vanadium as the beta stabilizing element, Ti-6Al-7Nb titanium alloy shows higher biocompatability than Ti-6Al-4V titanium alloy. The present research is designed to investigate the influence of annealling temper on the mechanical properties and microstructures of Ti-6Al-7Nb titanium alloy, by optical microscopic (OM) and scanning electron microscopic (SEM), and tensile test. The results show that the microstructures after recrystalization heat treatment comprise a mount of equiaxed alpha grains in the matrix of equiaxed beta phase with alpha (hcp)/ beta (bcc) platelets. The microstructures with partial recrystalization alpha phase possess better mechanical properties which conform to the ASTM F 1295 standard and ISO 5832-11 standard. Compared with Ti-6Al-4V titanium alloy and CP titanium alloy, Ti-6Al-7Nb titanium alloy is suitable to be used as implanted biomaterial devices to replace ill-functioning or missing tissues or organs.