Crystallization and electrochemical corrosion behaviors of amorphous and nanocrystalline Fe-based alloys

Amorphous Fe73.5Si13.5B9Nb3Cu1 alloy was prepared by the chill block melt-spinning process and nanocrystalline alloy was obtained by annealing. The crystallization behavior was analysed by DSC, XRD and TEM. The electrochemical corrosion behaviors in different annealed states were performed by linear polarization method and electrochemical impedance spectroscopy in 1mol/L HCl solution. The results show that the crystallization of amorphous alloy occurs in the two steps. Some nanometer crystals appear when annealing in 550°C and 600°C, respectively with grain size 13nm and 15nm. 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 consisted of only single semi-circle. The charge transfer reaction resistances increases as annealing temperature rises.