Corrosion behavior of Zr48Cu36Al8Ag8Six (x=0.00, 0.25, 0.50, 0.75, 1.00 at.%) bulk metallic glasses (BMGs) in sodium chloride and sulfuric acid solutions were investigated by immersion test, direct current (dc) polarization techniques (Tafel polarization, linear polarization resistance, potentiodynamic polarization) and electrochemical impedance spectroscopy. Instrumental analyses such as DSC, SEM, AFM were carried out prior to and post the corrosion test to find the correlation between the corrosion behaviour and structure of the BMG； EPMA and XPS analyses provided the relationship between the corrosion and composition of the specimens. According to the results from immersion test and electrochemical studies, we concluded that the specimens of BMG containing 0.25 at.%-Si revealed the best corrosion resistance. There was an occurrence of active - passive transition on the potentiodynamic polarization curve for the specimens immersed in sulfuric acid. The presence of passive film on the specimens was confirmed in terms of XPS analyses. Dominant contribution of the passive film indicated by the strongest peaks of ZrO2 and SiO2 led to the best corrosion resistance of the specimens with 0.25 at.%Si.
