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

Amorphous Fe_73.5Si_13.5B₉Nb₃Cu₁ 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 1 mol/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 13 nm and 15 nm. 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 Fe_73.5Si_13.5B₉Nb₃Cu₁ alloys both consisted of only single semi-circle. The charge transfer reaction resistances increases as annealing temperature rises.