Influence Of Magnetic Field Annealing On Structure And Magnetic Properties For Soft Magnetic Materials

(Fe0.5Co0.5)73.5Cu1Mo3Si13.5B9as well as (Fe1-xCox)73.5Si13.5Nb3B9Cu1(x=0.25,0.5,0.75) alloys and Ni0.2-xMgxCu0.3Zn0.5Fe2O4(x=0.05,0.1,0.15,0.2) ferrites weremade by melt quenching technique and Sol-gel method respectively. The main focusare concentrated on the crystalline volume fraction (Vcry), saturation magnetostriction(λs), effective magnetic anisotropy (<K>) and bulk density of ferrite (ρ) together withtemperature dependence of initial permeability (μi~T curves) in order to analyze theinfluence of magnetic field annealing (FA) on structure and magnetic properties of thesoft magnetic materials by comparing with vacuum annealing (NA) samples.X-ray diffraction (XRD) showed that two-phase nanocrystalline alloys composedof α-FeCo(Si) or (FeCo)3Si crystal phase and residual amorphous phase were obtainedafter vacuum annealing at proper temperature, and the Vcryincreases with annealingtemperature. Magnetic field annealing has no obvious effect on Vcry. FeCo-basednanocrystalline alloy with Fe:Co=1:1has much higher Vcryand excellenthigh-temperature soft magnetic properties. The λSof FeCo-based nanocrystallinealloys increases with annealing temperature but decreases after magnetic annealing.The value of <K> increases after longitudinal magnetic annealing because of theinduced a uniaxial anisotropy (Kμ). The bulk density and the Curie temperature ofNi0.2-xMgxCu0.3Zn0.5Fe2O4ferrites decrease with Mg content increasing.After magnetic field annealing, the change of λSand <K> caused acorresponding change in μi~T curves of FeCo-based nanocrystalline alloys. Magneticannealing is in favor of the magnetic domains rotation of two-step sintering ferrites,thus improving magnetic softness of the materials.