Annealing effect on the magnetic properties of cobalt-based amorphous alloys

The annealing effects on the magnetic properties of the Co72B19.2Si4.8Cr4 and Co64.8Fe7.2B19.2Si4.8Cr4 alloy systems are reported. Ribbon samples with 2 mm width and 20-30 μm thickness for both compositions were synthesized by melt spinning. The as-spun samples were subjected to annealing at various temperatures below their glass transition temperatures for 15 min in a vacuum. The annealed systems tended to have improved soft magnetic characteristics, including higher saturation magnetization and lower coercivity values, while maintaining their amorphous phase. A high saturation magnetization of 87.8 emu g−1 and low coercivity of 0.084 Oe were obtained for Co64.8Fe7.2B19.2Si4.8Cr4 after annealing at 400 °C, which is a significant improvement in comparison to the magnetic properties of the as-spun ribbons.