Electrochemical Behavior of Cu60Zr25Ti15 Bulk Metallic Glass with the Addition of Nb and Mo

This paper reports the changes in the electrochemical behavior of Cu60Zr25Ti15 bulk metallic glass (BMG) with the addition of 1 at.% Mo and Nb in 3.5 wt.% NaCl aqueous solution. Electrochemical methods employed for the study are open-circuit potential (OCP) and potentiodynamic polarization. The OCP values of the parent BMG and minor-alloyed BMGs differ only marginally. However, potentiodynamic studies show slightly higher corrosion resistance for the minor-alloyed BMGs than that of the parent alloy. Polarized surfaces of all the samples, examined under a scanning electron microscope (SEM), reveal pits formed due to corrosion. Corrosion products are analyzed by energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Higher corrosion resistance observed for Nb- or Mo-added BMGs is attributed to the formation of NbO2/Nb2O5 and MoO2, respectively, besides the oxides of other constituent elements.