Synthesis of FeSiBPNbCu nanocrystalline soft-magnetic alloys with high saturation magnetization

• Thermal stability of the FeSiBPNbCu alloys is strongly dependent on the Fe content.
• The FeSiBPNbCu alloys with high Fe content exhibit good soft magnetic properties.
• The coexistence of Cu, P and Nb leads to the excellent soft magnetic properties.

A series of [Fe0.76+x(Si0.4B0.4P0.2)0.24−x]98.25Nb1Cu0.75 (x = 0–0.08) nanocrystalline soft-magnetic alloys with high saturation magnetization were synthesized by adjusting Fe content and improving the crystallization behavior, soft-magnetic properties and microstructure. It is found that the temperature interval between the two crystallization peaks is significantly enlarged from 50 to 180 °C when the Fe content of the alloys increases from x = 0 to x = 0.08, which greatly expands the optimum annealing temperature range. The alloys with higher Fe content are prone to form more uniform nanocomposite microstructure with better thermal stability and soft magnetic properties. The Fe-rich FeSiBPNbCu nanocrystalline alloys with x = 0.08 exhibit excellent soft-magnetic properties, including the high saturation magnetic flux density of up to 1.74 T, low coercivity of about 3.3 A/m and high effective permeability of more than 2.2 × 104 at 1 kHz under a field of 1 A/m. The combination of excellent soft-magnetic properties, low cost and good productivity makes the FeSiBPNbCu alloys to be a kind of promising soft-magnetic materials for electrical and electronic industry applications.