Passive Layers and Corrosion Resistance of Biomedical Ti-6Al-4V and β-Ti Alloys

Abstract

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.

Electrochemical Behaviour of Ti and Ti-6Al-4V Alloy in Phosphate Buffered Saline Solution

“…EDS analysis of CP Ti (Table 6) shows the presence of Ti and O at varying amounts at positions 1-4, which indicates the fact that the entire surface of CP Ti is covered with a protective oxide layer of TiO 2 [6,10,17,20,41]. As already established, the oxide layer has a two-layer structure, and the outer part of the oxide layer is porous in nature.…”

“…For biomedical applications, corrosion behavior is one of the most important criteria because the human body is an aqueous electrolyte that contains different ions such as Cl − , PO 4 3− , HCO 3 − , OH − , Ca 2+ , Mg 2+ , H + , K + , Na + etc. [6]. Therefore, many research types were performed to understand better the corrosion behavior of titanium and its alloys in different simulated body fluids [7][8][9][10][11][12][13][14].…”

Mechanical Properties and Residual Stress Measurements of Grade IV Titanium and Ti-6Al-4V and Ti-13Nb-13Zr Titanium Alloys after Laser Treatment

“…This is confirmed by the tendency of titanium to oxidize in air. The passive layer of titanium oxide formed also increases the corrosion resistance [ 45 , 46 ].…”

Effect of thermomechanical treatment on structure and properties of metastable Ti-25Nb-8Sn alloy

“…Although the elastic modulus (110 GPa) of Ti-6Al--4V alloy is much lower than those of 316L stainless steel (205 GPa) and Co-Cr-Mo alloy (230 GPa) [1], it is still several times higher than that of human cortical bone . In addition, Ti-6Al-4V contains aluminum (Al) and vanadium (V) that are harmful to the human body [4,5]. In recent years, many β-type Ti alloys with low elastic modulus and without Al and V elements have been widely developed, such as Ti-5Nb-5Mo [6,7], Ti-26Zr-24Nb [8], Ti-Nb-Zr-Fe--O [9], Ti-Nb-Ta-O [10], Ti-20Nb-5Ag [11], and Ti-4Fe [12].…”