Electrochemical properties of amorphous metal alloys of Al-(Gd, Y)-Ni system in alkaline solution

Abstract

The study of the chemical activity of amorphous Al-Ni metal alloys with various additives determines the feasibility of their operation in various fields of technology. This is a pressing scientific and applied problem, therefore, there is a need for electrochemical study of oxide-hydroxide films on the surface of amorphous alloys with variable composition of alloying elements, such as yttrium and gadolinium in 0.5‑5.0 M KOH aqueous solutions. The self-determination of the electrode potential of the AMA electrodes, ie without external influences, in particular polarization, was investigated potentiometrically. It is found that the introduction of nickel and RE stabilizes the corrosion resistance of aluminum alloys in alkaline environments, and the nature of RE practically does not affect the stable value of the potential of AMA electrodes, the value of which ranges from ‑0.75 to ‑0.79 V. Potentodynamic conditions produced polarization curves, which were the basis for studying the features of electrochemical processes on the surfaces of the studied materials in different media. A tenfold polarization of the AMA ‑ electrode into the region of positive potentials was performed. The anode polarization time was 540 s. AMA‑electrodes were polarized in aqueous KOH solutions of different concentrations. Electrochemical transformation of AMA electrodes in media of different concentration of KOH solution from 0.5 to 5 M was investigated by voltammetric analysis at their polarization within the potentials from ‑1.7 to + 1.0V. It is shown that yttrium doping reduces the passivity of the alloy surface, especially in 5 M KOH, and the replacement of yttrium by gadolinium, the combined presence of yttrium and gadolinium stabilizes the corrosion properties within concentrations from 1.0 to 5.0 M, in particular, the corrosion potentials acquire stable values. and ten ‑0.75 ± 0.05 V. It is shown that Y doping reduces the passivity of the alloy surface, especially in 5 M KOH, and the replacement of Y with Gd, the combined presence of Y and Gd stabilizes the corrosion properties within concentrations from 1.0 to 5.0 M, in particular, the corrosion potentials become stable. Values within the range from -0.75 to -0.78 V. However, due to the tenfold polarization of the AMA electrodes within the potentials from -1.7 to + 1.0 V, the corrosion potentials of the Al 87 Ni 8 Y 5 and Al 87 Ni 8 Gd 5 AMAs in the cathodic side shift approximately 0.03 V. Keywords: amorphous metal alloys, corrosion resistance, rare earth metals, aluminium.