Influence Of Magnetic Field Annealing On The Soft Magnetic Properties For FeCo-based Nanocrystalline Alloys

The effect of magnetic field annealing on the soft magnetic properties of(Fe_0.5Co_0.5)_73.5Si_13.5B₉Cu₁Nb_3-xMo_x?x=0,1,2,3?and(Fe_0.9Co_0.1)_74.5Nb₂Si_17.5B₅Cu₁alloy was mainly studied.Meanwhile,the influence of Mo addition on high-temperature soft magnetic properties for air annealed FeCo-based nanocrystalline alloys was also investigated.The variation of?_s and<K>for magnetic field annealed nanocrystalline alloys were analysed.XRD and TEM were used to investigate the microstructure of nanocrystalline alloys.The variation of initial permeability for annealed nanocrystalline alloys with temperature was measured to study the effect of magnetic field annealing on high-temperature soft magnetic properties of alloys and the effect of Mo addition on oxidation resistance of FeCo-based alloys.Theexperimentalresultsshowedthatinthe(Fe_0.5Co_0.5)_73.5Si_13.5B₉Cu₁Nb_3-xMo_x?x=0,1,2,3?alloys,with the Mo content increasing,the Curie temperature is decreaed by about 5-10°C and the room-temperature initial permeability of annealed nanocrystalline alloys is declined.Magnetic field annealing decreases?_s but increases<K>.Magnetic annealing can effectively tailor the shape of?_i-T curves for the nanocrystalline(Fe_0.5Co_0.5)_73.5Si_13.5B₉Cu₁Nb_3-xMo_x?x=0,1,2,3?alloys.Although the room-temperature?_i of magnetic field annealed(Fe_0.5Co_0.5)_73.5Si_13.5B₉Cu₁Mo₃ alloy is smaller,the high-temperature?_i is higher.Therefore,magnetic field annealing improves high-temperature magnetic softness of(Fe_0.5Co_0.5)_73.5Si_13.5B₉Cu₁Mo₃ alloy.Although the Curie temperature of(Fe_0.5Co_0.5)_73.5Si_13.5B₉Cu₁Mo₃ alloy is decreased by5°Ccomparedwith(Fe_0.5Co_0.5)_73.5Si_13.5B₉Cu₁Nb₃alloy,air-annealed(Fe_0.5Co_0.5)_73.5Si_13.5B₉Cu₁Mo₃ alloy exhibits more stable initial permeability?_i at elevated temperatures and higher?_i above 490°C compared with air-annealed(Fe_0.5Co_0.5)_73.5Si_13.5B₉Cu₁Nb₃ alloy.Therefore,the replacement of Nb by Mo improves high-temperature magnetic softness of air-annealed FeCo-based alloys.These results might be significant for reducing costs and simplifying the manufacturing process.(Fe_0.9Co_0.1)_74.5Nb₂Si_17.5B₅Cu₁ alloy was investigated by vacuum and magnetic field annealing at different temperature.The room-temperature initial permeability decreases with the temperature increasing.Magnetic field annealing decreases?_s but increases<K>,and the initial permeability of magnetic field annealed samples is appreciably improved at room temperature.The high-temperature initial permeability is higher for(Fe_0.9Co_0.1)_74.5Nb₂Si_17.5B₅Cu₁ alloy with magnetic field annealing at540°C,so magnetic field annealing is helpful to improve the high-temperature soft magnetic properties.