Abstract:Ni_42.2W_19.2Fe_18.9B_19.7 (mole fraction, %) amorphous alloy was prepared by melt spinning method. The characteristic temperatures and precipitated phases of amorphous alloy were identified by differential scanning calorimeter (DSC) and X-ray diffractometer (XRD). The electrochemical corrosion behaviors of the samples in 3.5% NaCl (mass fraction) solution was studied by the linear polarization method and electrochemical impedance spectroscopy. The morphologies and components of samples after potentiodynamic polarization were observed and analyzed by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and micro-zone X-ray diffractometer, respectively. The result shows that the Ni_42.2W_19.2Fe_18.9B_19.7 amorphous alloy could be prepared by melt spinning method. The glass transition temperature and crystallization temperature are about 627 and 692 ℃, respectively. Compared with as-spun sample and the sample annealed at 750 ℃, the anticorrosion property of the sample annealed at 650 ℃ is obviously improved. A stable passive film forms on the surface of sample annealed at 650 ℃, which leads to its excellent corrosion resistance. However, the passive films on the surfaces of the amorphous alloy and the sample annealed at 750 ℃ are not stable, which are susceptible to be attacked by pitting corrosion and localized corrosion.

Key words: amorphous alloy; polarization curve; electrochemical impedance spectroscopy; electrochemical corrosion