Effects of Cu content on electrochemical response in Ti-based metallic glasses under simulated body fluid

Systematic characterization of the corrosion response of the Cu-free Ti₄₅Zr₄₀Si₁₅ and Cu-containing Ti₄₀Zr₄₀Si₁₅-Cu₅ and Ti₄₅Zr₂₀-Cu₃₅ metallic glasses (MGs) in the Hank's solution is conducted, in terms of the open circuit potential, potentiodynamic polarization, as well as electrochemical impedance measurements. The Cu role in the Ti-based MGs, tentatively to be applied for bio-implants, is established and modeled. The presence of nobler Cu will impose two opposite effects. The minor positive effect of minor shift of E_corr is not a major issue, but the negative effect on local pitting and ion release would cause a major drawback. The ICP-MS indicates that the release of Cu ions increases with increasing Cu content. For more promising anti-pitting ability, the Cu content in Ti-based MGs should be kept as low as possible, better to be none or less than about 5 at.%.