Influence of iron additives on the corrosion resistance of Al87Gd5Ni8 amorphous metal alloy

Based on the results of voltammetric investigations, we have shown that the partial replacement of nickel by 4 at. % Fe in Al₈₇Gd₅Ni₈ amorphous alloy leads to a decrease in the corrosion currents and an increase in the polarization resistance, which demonstrates the higher corrosion resistance of Al₈₇Gd₅Ni₄Fe₄ alloy. Using the method of electrochemical impedance spectroscopy, we have studied the durability and protective capacity of passivation oxide layers at electrodes made of this alloy in 0.1 M NaCl aqueous solution. We have also selected an impedance model of the formation of interfaces oxide–0.1 M NaCl and amorphous metal alloy–0.1 M NaCl. We have established that active diffusion redox reactions, described by the Warburg element, take place at the interface oxide film–0.1 M NaCl. The diffusivities of anions from the solution into the surface oxide layer have been calculated. Finally, we show that, with increase in the time of electrochemical reaction in 0.1 M NaCl aqueous solution, diffusion decreases due to the compaction of the surface oxygen-containing layers.