Electrochemical characterization of rapidly solidified Al-(Cr,Cu,Ni,Y,Zr)-Fe alloys

Abstract

The aim of this work was to investigate the multiphase structure of new Al71(Cr, Cu, Ni, Y, Zr)24Fe5 and Al65(Cr, Cu, Ni, Y, Zr)20Fe15 alloys, and the influence of chemical composition on their corrosion behavior. Samples were prepared using two different cooling rates: slowly cooled (master alloys), and rapidly solidified by high-pressure die casting into a water-cooled copper mold (plates). The structure of the studied alloys were investigated by X-ray diffraction (XRD), light microscopy, and Mössbauer spectroscopy. The crystallization mechanisms are described based on differential scanning calorimetry (DSC) heating and cooling curves. Electrochemical potentiodynamic measurements were conducted in 3.5% NaCl solution at 25 °C, and electrochemical impedance spectroscopy (EIS) tests were also carried out. The alloys were characterized by a multiphase crystalline structure, except Al65Cu20Fe15 and the plate form of Al71Ni24Fe5 alloy, for which a quasicrystalline phases were identified. Moreover, the complex metallic alloy (CMA) phase was detected for Al-Cr-Fe alloys. For samples in the form of plates, structure fragmentation was found. On the basis of the experimental polarization curves, extrapolation of Tafel curves and EIS results, the best corrosion properties were found for alloys with zirconium additions, while the alloys with addition of yttrium showed the least resistance.