Influence of static magnetic field on rapid solidified structure and nanocrystallization behavior of Fe–Si–B–Cu soft magnetic alloys with pre-existing α-Fe nanocrystals

Abstract

The effects of static magnetic field strength on the rapid solidified structure, thermal stability, crystallization structure and soft magnetic properties of melt-spun Fe81.6Si4B13Cu1.4 alloys were investigated and the corresponding related mechanism was discussed in terms of formation of pre-existing α-Fe crystals and nanocrystallization behaviors. The rise of magnetic field strength promotes the formation of the α-Fe crystals in as-spun alloy, enhances the competitive growth between the crystals during annealing, and then refines the crystals in the annealed alloy and improves their magnetic softness. The Fe81.6Si4B13Cu1.4 alloy prepared under 200 mT contains α-Fe crystals with a high number density and average size (D) of 8.3 × 1022 m−3 and 5.9 nm, respectively, in as-spun state, and possesses fine crystals with a D of 18.2 nm and excellent soft magnetic properties with a high saturation magnetization of 1.75 T, low coercivity of 9.2 A/m and high effective permeability of 10,160 at 1 kHz after annealing at 633 K for 60 min.