Electrochemical and Salt Spray Corrosion of FeCo-Based Bulk Amorphous Alloys

The corrosion resistance of Fe24+xCo24-xCr15Mo14C15B6Y2 (x=0, 2, 4, 6, 17) bulk amorphous alloy was investigated by electrochemical tests and neutral salt spray corrosion. The alloy forms a wide passivation zone in 1 mol/L HCl, and its EIS spectra are composed of a single capacitive loop, showing a good corrosion resistance. Combined with the results of polarization curves and AC impedance analysis, it suggests that the corrosion resistance of the alloy increases first and then decreases with the increasing of Co content. It gets the best corrosion resistance when the Co content is 20 at%. EDS and atomic force microscopy (AFM) were used to analyze the salt spray corrosion result. It indicates that the corrosion products are mainly composed of iron and cobalt oxides and their chlorides. Meanwhile, the corrosion degree of FeCo-based bulk amorphous alloys changes with the variation of Co content, and its salt spray corrosion resistance rule is consistent with the electrochemical corrosion resistance rule.