Study on Preparing and Crystallization Kinetics of Melt-Spun Co-Based Soft Magnetic Amorphous Alloy

Amorphous ribbons of Co68.5Fe4Si10B17.5 were prepared by a single roller melt-spinning technique in the air atmosphere. The crystallization products were analyzed by X-ray diffraction. The crystallization kinetics of the alloys were investigated by means of differential scanning calorimetry (DSC) in the mode isothermal annealing. It is found when the isothermal kinetics was modeled by the Johnson–Mehl–Avrami equation, the Avrami exponents are calculated to be in the range of 2.11–2.58 for different isothermal temperatures. This implies that the crystallization of Co68.5Fe4Si10B17.5 amorphous alloy is governed by either diffusion or interface controlled three-dimensional growth, depending on the annealing temperature. On the basis of the Arrhenius relation, the activation energy Ec in the isothermal process is calculated to be 113.67 kJ/mol. Finally, details of the nucleation and growth behaviors during the isothermal crystallization are discussed.