Research On Preparation And Properties Of Ti-24Nb-4Zr-7.9Sn Alloy

Ti-24Nb-4Zr-7.9Sn alloy is a new-type β biomedical alloy, with good mechanical properties, low modulus, high corrosion resistance and good biocompatibility.The dense was fabricated by powder metallurgy(PM) and spark plasma sintering (SPS). The effect of the sintering process on micro structure and properties of Ti-24Nb-4Zr-7.9Sn alloy was systematically investigated. Corrosion resistance and biocompatibility of the alloy was discussed by corrosion electrochemical experiments and simulated biological compatibility preliminary experimental.Results were shown as follows:1. Ti-24Nb-4Zr-7.9Sn was sintered in vacuum furnace by powder metallurgy.The best sintering process was at1250℃for2hours.The relative density,tensile strength,elongation,hardness and elastic modulus of the alloy reached97.2%,705MPa,5.6%,547Hv and35.1GPa,respectively.The microstructure was a typical Widmannstatten microstructure,which possessed β-phase and a-precipitation,the microstructure of the material is uniformly and dense, the grain size was about46μm. The fracture mechanism of the alloy was the coexistence of brittle and ductile rupture.2. High-density Ti-24Nb-4Zr-7.9Sn alloy was prepared by SPS within a relatively short time,the best sintering process was at1250℃. The relative density, tensile strength,elongation,hardness and elastic modulus of the alloy reached99.4%,789.5Mpa,6.4%,556Hv and34.53GPa respectively.The microstructure of the material was uniformly and dense, which possessed β-phase, the grain size was about45μm.The fracture mechanism of the alloy was ductile rupture.Comparison to powder metallurgy, preparation of Ti-24Nb-4Zr-7.9Sn alloy by SPS, the density,mechanical properties,elastic modulus and microstructure morphology of the alloy by SPS was better.3. The polarization curve was measured by using three electrode electrochemical systems. The resistance parameter,such as corrosion potential, the corrosion current density and polarization resistance was calculated in organism simulation fluid,the best corrosion resistance of titanium alloys by PM was at1250℃for2hours and the alloy sintered at1250℃for10minutes by SPS, the corrosion resistance of the alloy prepared by SPS at1250℃for10minutes was better than that of the alloy prepared by powder metallurgy.4. After the biological corrosion test on Ti-24Nb-4Zr-7.9Sn alloy, apart from rare pitting around the porosity of the alloy, and there were no signs of corrosion on the specimen’s surface.The alloy has excellent corrosion resistance.Compared to spark plasma sintering, the alloy by powder metallurgy titanium alloy have better biocompatibility in organism simulation fluid, all had good bio-inoxidizability.