Combinatorial Approach For Bio-titanium And The Phase Relations Of Ti-Co-Nb

Abstract:Titanium alloys have the following characteristics:low density, high mechanical strength, low elastic modulus, high corrosion resistance and excellent biocompatibility, and widely used in biomedical fields. Diffusion multiple of the Ti-Zr-Ta (Nb) system was manufactured, then annealed at1273K for1800h, and water quenched to room temperature. Combining nano-indentation and electron probe micro-analyze (EPMA), the elastic modulus, hardness as well as composition at each point of the diffusion multiple were determined. Based on the experimental data, the composition/elastic modulus/hardness database of the Ti-Zr-Ta (Nb) alloys were obtained. In addition, diffusion triple technique is applied to study the phase relations of Ti-Co-Nb system at1273K. The conclusion as following:1.In the Ti-Ta system, the elastic modulus is not continue to decrease with increasing β stable elements of Ta, and the elastic modulus changed showing the "W" shape, which is mainly related the phase transition from high-temperature (3-phase region to room temperature. Ti-Ta alloys reach the valley value of67.5GPa and67.8Gpa at28%and59%Ta, and Ti-37%Ta alloy owns the maximum hardness is4.0GPa. In ternary Ti-Zr-Ta system, Ti-38Zr-10Ta has a relative lower elastic modulus value of63.3GPa, and a relative larger hardness of3.4GPa. The Ti-38Zr-10Ta alloy is a promising candidate as metallic biomaterials for application.2. In the Ti-Nb system, the elastic modulus changed with increasing Ta showing the "W" shape. Ti-39%Nb alloy has the relative lower elastic modulus of63.5GPa, and Ti-21%Nb alloys has the relative higher hardness of4.1GPa. In Ti-Zr-Nb system, Ti-41%Zr-10%Nb has a lower elastic modulus value of62.7GPa, and a larger hardness of2.7GPa, which is a promising candidate as metallic biomaterials for application.3. The trend of elastic modulus is similar to those reports by handing one composition at a time, and the high-efficiency combinatorial approach has demonstrated to be an effective tool in accelerating metallic biomaterials research and discovery.4. An isothermal section of the Ti-Co-Nb ternary system at1173K is established. Ti, Nb can be replaced by each other in a certain extent, and NbCo2and TiCO2form a continuous solid solution (Ti,Nb)Co2. No ternary compound was found. Four three-phase equilibria are observed:(1)μ-Nb6Co7+(Ti,Nb)Co2+TiCo;(2) μ-Nb6Co7+TiCo+(Ti,Nb);(3)(Ti,Nb)Co2+TiCo2(c)+TiCo;(4) Ti2Co+TiCo+(Ti,Nb).