Magnetic softness and magnetization dynamics of FeSiBNbCu(P,Mo) nanocrystalline alloys with good high-frequency characterization

Abstract In this study, the microalloying effects of P and Mo on thermal behavior, magnetic softness and magnetization process of FeSiBNbCu(P,Mo) nanocrystalline alloys were investigated systematically. The P and Mo bearing alloys exhibit pronouncedly improved magnetic softness, including extremely low coercivity of about 0.7 A/m, high saturation magnetic flux density of about 1.40 T, high permeability over 3.0 × 10 4 at 1 kHz. The excellent magnetic softness could be attributed to uniform dual-phase microstructure and wide strip magnetic domains after optimum annealing. The P and Mo containing alloys also have good high-frequency characterization, especially, the permeability at 100 kHz is still over 1.53 × 10 4 . These alloys also have relatively low pinning field of 20–30 A/m, which means lesser defects and easier magnetization. Through observing the changes of magnetic domains and μ with applied field increasing, we found that the increase of μ is corresponding to reversible and irreversible movement of domain walls, after reaching the maximum, the decrease of μ is related to the rotation of magnetic moment and the split of domains.