Effect of chromium on the electrochemical properties of iron aluminide intermetallics

• The electrochemical properties of Fe3Al–xCr alloys with up to 5 at.% Cr were studied.
• Addition of Cr increases the pitting corrosion resistance of the intermetallic.
• Addition of Cr decreases the flat-band potential and enhances the resistance to hydrogen embrittlement.

The effect of chromium content on the electrochemical properties of Fe3Al intermetallics is examined. The susceptibility of alloys to pitting and crevice corrosion in solutions with different concentrations of Cl− ions was studied with the aid of cyclic polarization and galvanostatic methods. The form of the pits, and their concentration on different crystal orientations, was evaluated with the Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD) techniques. Additionally, Electrochemical Impedance Spectroscopy (EIS) and the Mott–Schottky (MS) methods were used to characterize the passive film. The results show the beneficial effect of Cr for corrosion and hydrogen embrittlement resistance.

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