Magnetic softness, dynamic magnetization, and relaxation behavior of FeSiBC amorphous alloys

The variation of dynamic coercivity, core loss, permeability (μ′), and relaxation behavior with annealing temperature, frequency as well as magnetic field magnitude (H_m) for the FeSiBC amorphous alloy was systematically studied. It can be found that the dynamic coercivity (H_cd) of 6.2 A/m at 1.0 T and 50 Hz is much larger than the static coercivity (H_cs) of 1.7 A/m for the optimally annealed Fe₇₈Si₈B₁₃C₁ alloy. The increase of H_cd with the increases in frequency can be ascribed to the difficulty of domain wall motion and magnetization rotation as frequency elevates. The dynamic magnetization analysis reveals that μ′ goes up and attains a peak value as H_m increases to about 25 A/m in the low frequency range, while the μ′ does not depend on H_m in the high frequency range (f > 10 kHz). In addition, the change of magnetic relaxation time with annealing temperature and filed magnitude is discussed.