Crystallization Behavior and Electrochemical Corrosion Characteristics of Amorphous Ni-Fe-W-B Alloy

57.5Ni-24.5Fe-14.5W-3.5B (wt%) amorphous ribbons were prepared by a melt spinning method, and then annealed at different temperatures. The crystallization process and evolution of phases were identified by differential scanning calorimeter and X-ray diffraction. A comparative study of the electrochemical corrosion behaviors of the samples was performed by the linear polarization method and electrochemical impedance spectroscopy in 3.5 wt% NaCl solution. The morphologies and components of the samples after potentiodynamic polarization were analyzed by SEM and EDS, respectively. The results. show that the crystallization process of the amorphous ribbons could be divided into three steps, and their crystallization temperature are about 430 degrees C, 470 degrees C and 700 degrees C. Compared with the completely amorphous alloy, the corrosion properties of the annealed amorphous sample increase obviously. A stable passive film is formed on the surface of the amorphous ribbon annealed at 500 degrees C, which contributes to its excellent corrosion resistance. However, the passive films on the surfaces of completely amorphous and amorphous samples annealed at 720 degrees C are not stable, which are susceptible to be attacked by pitting corrosion and localized corrosion.