Preparation and Electrochemical Corrosion Behavior of Amorphous and Nanocrystalline Fe-Based Alloys

Amorphous Fe73.5Si13.5B9Nb3Cu1 alloy was prepared by the chill block melt-spinning process and the nanocrystalline alloy was obtained by amorphous crystallization annealing. The crystallization behavior was analysed by DSC, XRD and TEM. The electrochemical corrosion behavior in different annealed states was investigated by linear polarization method and electrochemical impedance spectroscopy in 1 mol/L HCl solution. The results show that the crystallization of the amorphous alloy occurs in the two steps. Some nanometer crystals appear when annealed at 550 degrees C and 600 degrees C with grain size of 13 nm and 15 nm, respectively. The nanocrystalline alloy has higher corrosion potential and lower anodic current density than amorphous alloy. It indicates that nanocrystalline alloy has a higher corrosion resistance. Amorphous and nanocrystalline Fe73.5Si13.5B9Nb3Cu1 alloys both consist of only single semi-circle. The charge transfer reaction resistances increases as the annealing temperature rises.