Corrosion is an electrochemical process that results in the deterioration of the metal properties, due to its contact with aggressive environments. Metal destruction by corrosion occurs either through the transfer of the metal ions directly into corrosive solution or by continuous dissolution of a surface metal oxide. Uniform corrosive attack is less destructive than localized, causing catastrophic and suddenly damage of the corroding material, like in pitting corrosion. Rapid dissolution of a small localized area may occur through breakdown of passivity, initiation, propagation, and repassivation. The Ti and its alloys are mostly used in implants, because of their high corrosion resistance, due to the stable Tioxide formation caused by more cathodic behavior (Fig. 5.1) [55],

biocompatibility, and mechanical properties. Other alloys, like stainless steel are still in use.