THE APPLICATION OF EIS AND XPS TO INVESTIGATE THE DISSOLUTION AND PASSIVATION OF FE-CO BASE AMORPHOUS-ALLOYS IN KHCO3-K2CO3 BUFFERS

The corrosion behaviour of glassy Fe80-xCoxSi10B10 alloys (10 less tha n or equal to x less than or equal to 30) has been investigated and co mpared to that of high purity polycrystalline Fe and Co electrodes in carbonate-bicarbonate solutions. Electrochemical Impedance Spectroscop y (EIS) and X-ray Photo-electron Spectroscopy (XPS) measurements were performed under different polarization conditions. Results indicate th at the dissolution and passivation reactions of Fe-Co amorphous alloys differ significantly from those of pure polycrystalline metallic comp onents. The metal concentration ratio at the metal/solution and metal/ film/solution interfaces as well as composition and morphology of the surface layers are important factors in determining the dissolution an d passivation of the glassy alloys.