Abstract
It is a fact that, because of its poor performance characteristics, aluminium with high concentrations of iron, silicon and other impurities fails to find an industrial application. Hence, the development of new alluminium-based alloys appears to be a very important task. One of the promising compositions observed on the aluminium-iron diagram is a eutectic (α-Al+Al3Fe), which, having a minimum crystallization interval, corresponds to 2.18%(wt.) of iron content. This composition was taken as a model alloy and was inoculated with lithium, beryllium, and magnesium. The objective of this work is to establish what effect the above additives can produce on the corrosion resistance and the electrochemical behaviour of the model alloy of АZh2,18 in the NaCl medium. To achieve this objective, the anodic behaviour of the АZh2,18 alloy inoculated with the above metals was studied on the potentiostat PI-50.1.1 using the potentiostatic method in a potentiodynamic mode with the potential sweep speed of 2 mV/s. It is shown that, in the NаCl electrolyte, as the inoculant concentration increases, the free corrosion potential (or, fixed potential) of alloys travels in the direction of increase of the coordinate axis, whereas as the concentration of chloride ion rises, the fixed potential of alloys travels in the direction of decrease of the coordinate axis. As the chloride ion concentration in the electrolyte increases, the pitting and repassivation potentials of alloys drop. A higher concentration of inoculants in the original АZh2,18 alloy leads to rising pitting and repassivation potentials in all the media regardless of the chloride ion concentration. As the chloride ion concentration rises, the corrosion current density and, correspondingly, the corrosion rate of the alloys increase, whereas inoculants cut them down twice. These findings can be used for the development of new aluminum-iron alloys applicable in multiple industries.
Keywords
AZh2,18 alloy, lithium, beryllium, magnesium, potentiostatic method, electrochemical corrosion, anodic behaviour, corrosion potential, corrosion rate.
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