Progress of Ultrafine-Grain Ti and Its Alloys Prepared by ECAP for Biomedical Applications

Ti and its alloys have become one of the most widely used biomedical metal materials due to their lightweight, low elastic modulus, excellent biocompatibility, and superb osseointegration. However, their low plasticity, inferior corrosion resistance, and poor wear resistance restrict the development and applications of Ti and its alloys. Severe plastic deformation is considered as one of the most effective methods for grain refinement of metal materials. Additionally, equal channel angular pressing (ECAP) is the commonly used preparation method for bulk ultrafine-grain (UFG)/nanocrystalline metal materials. Through ECAP deformation, UFG Ti and its alloys with superior comprehensive properties can be prepared. In this research, the progress of ECAP preparation for biomedical UFG Ti and its alloys was reviewed. The effects of ECAP deformation on the microstructure, mechanical properties, corrosion resistance, and wear resistance of Ti and its alloys were discussed. The deformation and grain refinement mechanisms were analyzed. The development direction of further optimization in the properties of Ti and its alloys through ECAP coupled with traditional plastic working methods and post-deformation heat treatment was proposed.