Design And Research On Properties Of New Type Metastable β Titanium Alloys With Low Elastic Moduli For Biomedical Applications

Titanium alloys have been the most widely used for surgical implant materials to date because of its excellent combination of biocompatibility, corrosion resistance and mechnical properties among metal biomedical materials. But the moduli of present titanium alloys developed are still greater compared with that of bone. And it will lead to stress shielding and bone resorption because the moduli of elasticity do not match between implant materials and bone.Then the implant materials loose or fracture and this will result in implanting failure at last. Hence titanium biomaterials research is done by focussing on new type titanium alloys with lower moduli of elasticity.Composed of non-toxic elements Nb, Zr and Mo, three new type metastableβtitanium alloys for biomedical applications Ti35Nb10Zr, Ti35Nb8Zr2Mo and Ti20Nb15Zr10Mo with lower elastic modulus in theory were designed based on the d-electron alloy design method in this study. The designed alloys were prepared by WK-Ⅱvacuum unconsumable electrode arc skull furnace. Then we observed the microstructure, determined the phase constitutions and investigated the basic mechanical properties of designed alloys. The elastic modulus of these alloys were measured mainly, and effects of different chemical components and heat treatments on moduli were also studied. In addition, corrosion resistence of designed alloys were evaluated in an artificial physiological solution. The results listed as follows:1. The XRD analysis results indicate that onlyβphase exists in the skull castings and as-solutionized designed alloys.2. The results of microstructural observations using an optical microscope and a scanning electron microscpe indicate that crystal grains of designed alloy are large and averageβgrain size of skull castings are about 200μm. The differences of the averageβgrain size of designed alloys before and after heat treatments are slight. 3. The lowest compressing elastic moduli of Ti35Nb10Zr is 11.2GPa, Ti35Nb8Zr2Mo is 17.7GPa, and Ti20Nb15Zr10Mo is 14.7GPa when these alloys subjected to each heat treatments. The values are lower than that of Ti6Al4V(forged),which is 21.8GPa. The data also indicate that designing titanium alloys with low modulus using d-electron alloy design method could reduce experiments and cost and have perfect results.4. The corrosion resistence of designed titanium alloys in Hank's artificial simulated body fluid were tested by using electrochemical methods. The results indicate that these alloys have good corrosion resistence.