Microstructure And Biological Property Of Ti-X (Ge, Ga) Alloys

New series of Ti-xGe(x=2,5,10,20wt.%) and Ti-xGa (x=5,10,15,20wt.%) binary alloys were produced in this work by vacuum arc melting, and various experiments have been carried out to investigate the phase composition, microstructure, mechanical properties, in vitro electrochemical and immersion corrosion behaviors as well as the cytotoxicity with pure titanium as control, aiming to study the feasibility of the two Ti-X binary alloys as potential dental materials.The results show that the microstructure of the Ti-Ge alloys changes from single a-Ti phase toα-Ti+Ti5Ge3 precipitation phase with the increase of Ge content. Mechanical test results show that the best comprehensive mechanical properties lies in Ti-Ge alloy with the composition point at 5wt.%. The electrochemical corrosion behavior of Ti-Ge alloys indicates that Ti-2Ge and Ti-5Ge alloys show similar corrosion resistance like pure Ti in artificial saliva and even better corrosion resistance in fluorine-containing solution. However, Ti5Ge3 precipitation phase and the a-Ti matrix, owing to their different potential, could form corrosion galvanic cell to result in the galvanic corrosion, which deteriorate the corrosion resistance of Ti-Ge alloys with high Ge-content. According to our immersion corrosion test results, the daily Ge ion releases for all Ti-Ge alloys in the harshest test environment are much lower than the daily intake of Ge from foods for human, which are thought to be in the acceptable range. The in vitro cytotoxicity test indicates that Ti-Ge alloy extracts show no obvious reduction of cell viability to L929 fibroblasts and MG63 osteosarcoma cells, similar to CP Ti which is generally acknowledged to be biocompatible. Ti-xGe alloys (x<7wt.%) is a better candidate materials for dental restoration.Ti-xGa alloys (x<17wt.%) mainly consist of singleα-Ti phase. Ti-15Ga shows greatly improved mechanical properties when compared with pure Ti. Wear resistance under both dry and wet wear conditions and hardness of Ti-Ga alloys increase with the increasing Ga content. The electrochemical tests indicate that the corrosion resistance of Ti-Ga alloys is close to that of pure Ti in artificial saliva, which demonstrats that the alloying of Ga to pure Ti doesn't deteriorate the excellent corrosion resistance of Ti. In fluorine-containing solution, Ti-Ga alloys repassivate quickly after the breakdown of the passiovation, which prevent the alloys from further severe corrosion. However, the repassivation for pure Ti happens when the current density has increased to a very high level. The in vitro cytotoxicity test shows that the in vitro cytotoxicity grade of Ti-Ga alloys for L929 fibroblast cells and MG63 osteosarcoma cells is 1 grade, namely mild toxicity. However, the viability of L929 and MG63 cell lines doesn't show falling tendancy with the increase of Ga content in the testing alloys. Ti-xGa alloys (x<20 wt.%) is a better candidate materials for dental restoration.