Study On The Mechanical Properties Of A New Kind Titanium Alloy Ti-15Mo-3Zr-2Sn For Biomedical Application

According to the exploitation status quo and existing flaws of biomedical titanium alloys, a new kind of titanium for biomedical application is designed and fabricated, and its mechanical properties, microstructure and the influence of solid solution treatment and aging treatment on its mechanical properties are studied in this thesis. The concrete contents and results are as follows:1. A new biomedical titanium alloy Ti-15Mo-3Zr-2Sn is designed and fabricated.According to the characteristic of traditional titanium alloys for bone implant, the alloy to-be-designed is confirmed as near- β near type. Based on the influence of each pure metal on the mechanical properties and Young's modulus, Mo, Zr and Sn are selected as the intensification elements for their excellent biocompatibility, also Mo is as the β -phase stabilizer, and Zr, Sn good for next step machining. Considering Mo.Eq requirement and the suitable content of each element in near- β titanium alloy, the alloy as ascertained as Ti-15Mo-3Zr-2Sn.The designed alloy was fabricated by non-consumable vacuum arc smelting furnace, and the problem of the volatilization of Ti and Sn was successfully solved by fulfilling highly pure Ar gas with high pressure (up to5×104—1×105Pa), and a proper arrangement of the raw materials also benefits. The weight loss rate before and after smelting is smaller than 0.4%, and EDS analysis results also showed precision of the ingredient.2. The influence of heat treatment on the mechanical properties of the alloy was studiedThe alloy after hot forging possesses much higher surface hardness than that of pure Ti, and a 30% lower compression modulus than that of Ti-6A1-4V with comparable compression strength and higher hardness, which will make it more satisfactory in wear resistance as surgery implants.The phase-transformation point is estimated to be 750 ℃ around by Ti-Mo binary phase diagram, on which the solid solution treatment tests were carried and the optimum process was determined as 820℃/20min+WQ.The alloy aging at 790 ℃ and 820 ℃ possesses lower compression strength, compression modulus and hardness than that of hot-forged alloy, and outstanding plasticity, but the alloy solution treated at 760 ℃ has negative relation for the precipitation of a phase.Dispersion strengthening of the alloy by the precipitation of large mounts of fine α particles when aging-treated provides higher compression strength and modulus. But long time aging is not a good way to increase the strength for the crystal grain growing.Alloys aging-treated at higher temperature possess lower compression strength and modulus than those treated at lower temperature for the comparably smaller α phase volume content. If needed, alloy aging at 520 ℃ for 90min or longer will provide the highest compression strength.