Cyclic-anodic-polarization studies of a Zr_41.2Ti _13.8Ni₁₀Cu_12.5Be_22.5 bulk metallic glass

Cyclic-anodic-polarization tests were conducted on a Zr-based bulk metallic glass (BMG) with a chemical composition of Zr_41.2Ti _13.8Ni₁₀Cu_12.5Be_22.5 [Liquidmetal-001, LM-001 (at.%)]. Samples were compared in two different electrolytes at two different temperatures. Tests were conducted at 22 and 37 °C in both, an aerated 0.6 M NaCl electrolyte and a phosphate-buffered saline (PBS) electrolyte with a physiologically relevant dissolved oxygen content. For all tested conditions, the alloy demonstrated passive behavior at the open-circuit potential with low corrosion rates. However, a susceptibility to localized pitting corrosion was observed in all of the tested conditions. At both temperatures, statistical analyses revealed that the LM-001 BMG exhibited comparable or improved values for every corrosion parameter in the PBS electrolyte, as compared to the NaCl electrolyte. The mean differences between the protection potentials and the open-circuit corrosion potentials were determined to be positive values with greater magnitudes for the PBS electrolyte. Thus, the material may undergo pitting corrosion at surface flaws or after incubation-time periods, depending on the local and bulk environments, with lower probabilities for the PBS electrolyte.