Effect of surface crystallization on magnetic properties of Fe82Cu1Si4B11.5Nb1.5 nanocrystalline alloy ribbons

In this study, Fe82Cu1Si4B11.5Nb1.5 nanocrystalline alloy ribbons with completely amorphous structure and surface crystallization were prepared using melt-spinning technique with wheel speeds of 45 m/s, 35 m/s and 25 m/s. The effect of surface crystallization layers on the soft-magnetic properties, core loss and dynamic magnetization process were systematically investigated. Moreover, the permeability-frequency spectra were measured as a function of the AC magnetic field, ranging from 1 to 75 A/m. It was found that decreasing the melt-spinning wheel speed can widen the annealing temperature range and the coercivity increases with the increase of surface crystallization. Excessive crystallization layers will increase the pinning field (Hp), which will lead to an increase of magnetic anisotropy constant K and eventually decrease the effective permeability. The crystallization mechanism of the Fe82Cu1Si4B11.5Nb1.5 nanocrystalline alloy ribbons with surface crystallization layers was discussed from the aspects of diffusion and competitive processes, which is helpful for further understanding the nanocrystallization process.