Effect of immersion time on electrochemical and morphology of new Fe-Co metal-metal glassy alloys in acid rain

Electrochemical behavior of two Metal-Metal glassy alloys Fe78Co9Cr10Mo2Al1 (VX9) and Fe49Co49V2 (VX50) (at.%) were investigated at different immersion times in artificial acid rain at 20 degrees C using electrochemical techniques as electrochemical impedance spectroscopy (EIS) and cyclic polarization (CP). The morphology and composition of alloy surface were investigated using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX) measurements and atomic force microscopy (AFM). VX9 alloy has high corrosion resistance more than VX50 due to good protective elements as Cr 10% that create chromium oxide. Immersion measurements during (0.5-12 h) reveal the critical time for VX9 alloy is about 3 h to begin corrosion resistance while the VX50 alloy take a longer time to form protective film. The susceptibility of studied alloys for localized corrosion was observed by cyclic-polarization data due to passive film of two layers (inner compact and outer prose). The VX50 alloy has low value of charge transfer resistance due to exposure to more pitting attack. The AFM and SEM images found that average surface roughness (Ra) of VX9 alloy is lower than VX50 alloy. (C) 2018 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University.