Magnetic properties of Fe-6.4 wt.%Si ribbons

Thin Fe-6.4wt.%Si ribbons were produced by melt spinning. High-temperature recrystallizations, performed at 1025°C in a hydrogen atmosphere, were found to produce the lowest H_c values (19 A/m). Further agings were carried out at 50°C intervals in the range 400-700°C to optimize the magnetic properties. For all ribbons, H_c (60 Hz and DC), the maximum permeability, the saturation magnetostriction, and the effective anisotropy constant were measured. In general, the agings did little to improve the magnetic properties, and those around 600°C resulted in their deterioration. Extensive transmission-electron-microscope investigations of the ribbons indicate that the dendritic structure of the as-cast material disappears after recrystallization, leading to a more uniform distribution of Si as well as a more homogeneous ordering. The 600°C aging results in a marked anisotropy in the B2 antiphase boundaries and the growth of oxide particles, which lead to a deterioration of the magnetic properties