Research and development of biomedical titanium alloys for surgical implant materials

Titanium and its Titanium alloys as biomedical materials is becoming more and more attractive due to their lower density and lower elastic modulus, high ratio of strength vs. density, fine corrosion resistance and workability, especially its excellent biocompatibility compared with the conventional biomaterials such as stainless steel 316L and Co-Cr alloys. The commercial pure Ti and their alloys such as Ti-6Al4V, Ti-3Al-2.5V, Ti-5Al-2.5Fe and Ti-6Al-7Nb have been developed and used in clinic applications. However, the elastic modulus of these Ti alloys are still much higher than that of human bones which can lead to stress-shielding, and the potential toxic elements such as V, Al and Fe should be deleted to further improve the biocompatibility, and their wear resistance should be also further raised. Therefore it is necessary to develop new β-type of biomedical Ti alloys which are suitable for substituting and repairing of human joint, bone and tooth etc (See Fig.1). The paper first summarized the category, characteristic, R & D, and application of biomedical Titanium and its Titanium alloys. Then the alloy designing, melting, processing, heat treatment and microstructure, surface modification and et al of β type Titanium alloys, which are mainly used in surgical implant material, were mostly introduced. (See Table 1) In the end, two kinds of newly developed near β-type biomedical Ti alloy TLE1, TLE2 were designed and researched. After alloy ingots melting, forging, rolling and heat treatment, it is discovered that the two biomedical alloys possess excellent comprehensive properties, which the lowest elastic modulus (E) of alloys is 50. GPa or so and the fracture toughness (K_IC) reach to more than 90MPa M at high strength level by means of special processing and solid solution and ageing treatment (See table 2). The regularities of microstructure and mechanical properties were also investigated.