To evaluate the performance of Zr65Al7.5Ni10Cu17.5 amorphous alloy for the biomedical use, the effects of chloride ion, Cl-, pH, and dissolved oxygen, DO, on the anodic polarization behavior of the alloy were examined in phosphate buffered solutions. Polarization resistance, Rp, at open-circuit potential, Eopen, and pitting potential, Epit, were determined from the polarization curve. Compositions of passive film generated in a pH-7.5 solution with various concentrations of DO were characterized with X-ray photoelectron spectroscopy. In the solution with pH 7.5, the Epit decreased with the increase in logarithm of Cl- concentration, [Cl-], and showed the highest value with the same DO concentration, [DO], as that in vivo. The concentrations of hydroxide group, [OH-], and phosphate ions, [HxPO4(3-x)-], in the passive film were changed with various [DO]s, and the Epit decreased with the increase in [OH-] and [HxPO4(3-x)-]. In the solution with pH 2.2, the Epit was higher than the Eopen with and without DO. Therefore, this alloy may be resistant to the pitting corrosion in vivo.
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