Corroison Resistivity of Amorphous Iron Alloys Containing Chromium

In order to evaluate the corrosion resistivity of amorphous iron alloys which have been characterized by outstanding mechanical properties, immersion tests and electrochemical measurements of the amorphous alloys were carried out in acidic and neutral solutions. In a 1 N NaCl solution at 30℃, 0.01-1 N HCl solutions at 30℃ and in 10% FeCl_3・6H_2O solutions at 40 and 60℃, pitting corrosion did not occur on the amorphous Fe-Cr-P-C and Fe-Cr-Ni-P-C alloys and the weight change of the alloys containing 8 at% or more Cr was not detected by a microbalance after immersing for 168 hr. The critical potential for pitting did not appear on polarization curves of the amorphous alloys and the anodic current higher than 10^A/cm^2 was not observed over the potential range 0 to 0.5 V (SCE) in 1 N NaCl and 0 to 0.9 V (SCE) in 1 M H_2SO_4 by the potentiostatic anodic polarization of the alloys containing 8 at% or more Cr. The extremely high corrosion resistivity of the amorphous iron alloys is attributed to the peculiar film formation partly by the presence of Cr and a large quantity of P in the alloys and partly by a single phase of the amorphous state