Development and Application of Biomedical Ti Alloys Abroad

Research and development of titanium and titanium alloys for biomedical applications abroad during last years were reviewed. Several kinds of low Young's modulus, high mechanical properties, nontoxic and allergy-free beta-type titanium alloys were developed to replace the widely used Ti-6Al-4V alloy. In order to reduce the Young's modulus of the metals to a level similar to that of cortical bone, it is very effective to make titanium and its alloys porous and to adjust their porosity. The decrease in the strength of porous titanium can be significantly inhibited by penetrating polymer into the porous titanium through pressing, by which the biocompatibility can also be further improved. In order to meet the requirements in orthopaedic surgery field, porous TiNi superelastic shape memory alloy has been developed to overcome the drawbacks like weak interfacial bonds and mismatch of Young's modulus between bone and implants. In addition, several kinds of nontoxic and allergy-free beta-type superelastic shape memory titanium alloys were developed to substitute TiNi alloy with the aim to assure a more safety use in medical field. A tremendous number of surface modification techniques related to the deposition of modified surface layer and surface hardening were developed to improve the biocompatibility and wear resistance of titanium implants.