Microstructures and magnetic properties of amorphous Fe–Si–B–Ni alloy ribbons

Amorphous Fe76Si9B13Ni2 alloy ribbon cores of strip wound configuration were fabricated to measure core inductance as the function of an applied magnetic field at 200 kHz. The maximum core inductance ratio of 37.5–0 Oe applied magnetic field was obtained in 5 h annealed ribbon cores. In order to understand the behaviors of core inductance with annealing, the crystallization and the magnetic properties of the ribbons has been studied by transmission electron microscopy, scanning electron microscopy, X-ray diffraction and vibrating sample magnetometer. The ribbons were annealed for 1 h at 460°C to initiate crystallization in the localized area by forming three branch type α-(Fe, Si) dendrites and for 5 h by forming four branch type α-(Fe, Si) dendrites in the whole area. The dendrites kept the size of 200 nm up to 5 h annealing and started to grow rapidly after 6 h annealing, which was well matched with the maximum core inductance ratio.