Corrosion behavior of the Mg₆₅Cu₂₅Gd₁₀ bulk amorphous alloys

The corrosion behavior of the Mg₆₅Cu₂₅Gd₁₀ (numbers indicate at.%) bulk amorphous alloy as well as its crystalline counterpart and pure Mg investigated by electrochemical measurements. Potentiodynamic polarization tests and electrochemical impedance spectroscopy were carried out in 0.2 M borate buffer solution, 0.02 M NaCl solution and 0.1 M NaOH solution. Both amorphous and crystalline alloys were spontaneously passivated at significantly low passivation current density in borate buffer solution and sodium hydroxide solution. Surface morphology and composition information after polarization samples were characterized using scanning electron microscopy and energy disperse X-ray. Mg₆₅Cu₂₅Gd₁₀ bulk amorphous alloy shows higher corrosion resistance than its crystalline counterpart due to the absence of the heterogeneities in the former On the other hand, in Cl^- containing solution, both amorphous and crystalline alloys are active dissolved at high current density due the presence of aggressive Cl^- ion in solution.