Compared with stainless steel and Co–Cr‐based alloys, Ti and its alloys are widely used as biomedical implants due to many fascinating properties, such as superior mechanical properties, strong corrosion resistance, and excellent biocompatibility. After briefly introducing several most commonly used biomedical materials, this article reviews the recent development in Ti alloys and their biomedical applications, especially the low‐modulus β‐type Ti alloys and their design methods. This review also systemically investigates the recently attractive progress in preparation of biomedical Ti alloys, including additive manufacturing, porous powder metallurgy, and severe plastic deformation, applied in the manufacturing and the influenced microstructures and properties. Nevertheless, there are still some problems with the long‐term performance of Ti alloys, and therefore several surface modification methods are reviewed to further improve their biological activity, wear resistance, and corrosion resistance. Finally, the biocompatibility of Ti and its alloys is concluded. Summarizing the findings from literature, future prediction is also conducted.

β-type titanium (Ti) alloys have attracted a lot of attention as novel biomedical materials in the past decades due to their low elastic moduli and good biocompatibility. This article provides a broad and extensive review of β-type Ti alloys in terms of alloy design, preparation methods, mechanical properties, corrosion behavior, and biocompatibility. After briefly introducing the development of Ti and Ti alloys for biomedical applications, this article reviews the design of β-type Ti alloys from the perspective of the molybdenum equivalency (Mo_eq) method and DV-Xα molecular orbital method. Based on these methods, a considerable number of β-type Ti alloys are developed. Although β-type Ti alloys have lower elastic moduli compared with other types of Ti alloys, they still possess higher elastic moduli than human bones. Therefore, porous β-type Ti alloys with declined elastic modulus have been developed by some preparation methods, such as powder metallurgy, additive manufacture and so on. As reviewed, β-type Ti alloys have comparable or even better mechanical properties, corrosion behavior, and biocompatibility compared with other types of Ti alloys. Hence, β-type Ti alloys are the more suitable materials used as implant materials. However, there are still some problems with β-type Ti alloys, such as biological inertness. As such, summarizing the findings from the current literature, suggestions forβ-type Ti alloys with bioactive coatings are proposed for the future development.

The high specific strength, good corrosion resistance, and great biocompatibility make titanium and its alloys the ideal materials for biomedical metallic implants. Ti-6Al-4V alloy is the most employed in practical biomedical applications because of the excellent combination of strength, fracture toughness, and corrosion resistance. However, recent studies have demonstrated some limits in biocompatibility due to the presence of toxic Al and V. Consequently, scientific literature has reported novel biomedical β-Ti alloys containing biocompatible β-stabilizers (such as Mo, Ta, and Zr) studying the possibility to obtain similar performances to the Ti-6Al-4V alloys. The aim of this review is to highlight the corrosion resistance of the passive layers on biomedical Ti-6Al-4V and β-type Ti alloys in the human body environment by reviewing relevant literature research contributions. The discussion is focused on all those factors that influence the performance of the passive layer at the surface of the alloy subjected to electrochemical corrosion, among which the alloy composition, the method selected to grow the oxide coating, and the physicochemical conditions of the body fluid are the most significant.

Undesired damages (e.g. corrosion, wear) always take place on the surfaces of materials, which may lead to the dramatical degradation of materials and cause disastrous failure. As described in the article, number 1901258, by Lai-Chang Zhang, Liang-Yu Chen, and Liqiang Wang, surface modification endows the materials with better surfaces to protect against the damages from the environment surrounded and extends their lifetime in service.