Effects of Annealing Time on the Structure Characteristics and Magnetic Properties of FeSiBPCCuNb Amorphous Ribbons

In this paper, the structure characteristics and magnetic properties of Fe83Si6B6P1.5C1.5Cu1Nb1 amorphous alloy ribbons annealed at 550 °C for different times were systematically investigated using X-ray diffraction, vibrating sample magnetometer, and atom probe chromatography. The results show that high-density Cu atomic clusters of appropriate sizes help to stabilize the α-Fe(Si) phase and improve the uniformity of the grains to enhance the soft magnetic properties. The solubility difference between the α-Fe(Si) phase and the B-rich phase, the formation of a localized amorphous structure in the transition region, and the inhibition of nanograin growth. However, when the annealing time is extended, the size of the α-Fe(Si) grains decreases, the grain boundary density increases and secondary phases such as Cu clusters become pinning sites for magnetic domain walls. This leads to a decrease in soft magnetic properties, an increase in hard magnetic properties, and a rapid increase in coercivity. When annealed at 550 °C for 20 min, the number density of Cu atomic clusters was 9.18 × 1022 m−3, the spherical equivalent radius was 1.13 ± 0.29 nm, and the ribbons had good soft magnetic properties with a coercivity of 4.59 Oe. The saturation magnetic induction reached a peak value of 185.11 emu/g.