The Effect of Annealing on the Soft Magnetic Properties and Microstructure of Fe₈₂Si₂B₁₃P₁C₃ Amorphous Iron Cores

This research paper investigated the impact of normal annealing (NA) and magnetic field annealing (FA) on the soft magnetic properties and microstructure of Fe₈₂Si₂B₁₃P₁C₃ amorphous alloy iron cores. The annealing process involved various methods of magnetic field application: transverse magnetic field annealing (TFA), longitudinal magnetic field annealing (LFA), transverse magnetic field annealing followed by longitudinal magnetic field annealing (TLFA) and longitudinal magnetic field annealing followed by transverse magnetic field annealing (LTFA). The annealed samples were subjected to testing and analysis using techniques such as differential scanning calorimetry (DSC), transmission electron microscopy (TEM), X-ray diffraction (XRD), magnetic performance testing equipment and magneto-optical Kerr microscopy. The obtained results were then compared with those of commercially produced Fe₈₀Si₉B₁₁. Fe₈₂Si₂B₁₃P₁C₃ demonstrated the lowest loss of P_1.4T,2kHz = 8.1 W/kg when annealed in a transverse magnetic field at 370 °C, which was 17% lower than that of Fe₈₀Si₉B₁₁. When influenced by the longitudinal magnetic field, the magnetization curve tended to become more rectangular, and the coercivity (B_3500A/m) of Fe₈₂Si₂B₁₃P₁C₃ reached 1.6 T, which was 0.05 T higher than that of Fe₈₀Si₉B₁₁. During the 370 °C annealing process of the Fe₈₂Si₂B₁₃P₁C₃ amorphous iron core, the internal stress in the strip gradually dissipated, and impurity domains such as fingerprint domains disappeared and aligned with the length direction of the strip. Consequently, wide strip domains with low resistance and easy magnetization were formed, thereby reducing the overall loss of the amorphous iron core.