Biomaterials have always been the focus of material scientists and engineers. Titanium and its alloys have favorable properties, such as high strength, low density, good corrosion resistance, non-toxicity, low elastic modulus, biocompatibility, etc. Thus, Ti alloys have received much attention from scientists and engineers who work with biomaterials. Among these properties, the elastic modulus is a very important property for implant biomaterials because it avoids the “stress shielding” effect. In this study, we summarized low elastic modulus titanium alloys, which have great application potential for implant biomaterials. The major series of titanium alloys with low elastic modulus, including TiNb-based, TiMo-based, and TiZr-based series of titanium alloys, were discussed. The research status and the possible factors related to the low elastic modulus of these major titanium alloys were analyzed. Finally, the development prospects of the above series of low elastic modulus titanium alloys were compared, and the future direction of low elastic modulus Ti alloys as biomaterials was proposed.

Ti alloys have many excellent properties, including low elastic modulus, desired corrosion resistance, nontoxicity, and biocompatibility. Hence, they promise to be major hard-tissue implant biomaterials (HTIBs). However, some properties, like surface hardness, wearability, and cellular activity, need to be enhanced. Moreover, their corrosion resistance in simulated body fluids and biocompatibility also need to be investigated systematically before practical applications. As HTIBs, the primary properties in clinical applications are wearability, corrosion resistance, and biocompatibility. Surface modification is a commonly used effective way to improve the above-mentioned disadvantages. This work is a brief review of the main surface modification technologies of Ti alloys for HTIBs (hereafter referred to as Ti alloys). The main surface modification technologies of Ti alloys are divided into four types, namely, physical technologies, chemical technologies, electrochemical technologies, and surface plastic deformation technologies. The principle and applications of these four types of surface modification technologies on Ti alloys are introduced one by one. Finally, the future directions for the surface modification of Ti alloys are proposed.