Preparation And Magnetic Properties Of Fe-based Soft Magnetic Dual-phase Alloys With Low Permeability

With the distinctive requirements of common mode chokes,high frequency transformers and high precision current transformers with anti-bias current capability,a new type of Fe-based dual-phase soft magnetic materials with low permeability,high linearity and low loss have been developed.And it is suitable for industrial production.Fe(Co)NiCuNbSiB series alloy were studied.The effects of Co and Ni content and heat treatment on the magnetic permeability,linearity of B-H loop and core loss of the alloy were systematically studied.The magnetization mechanism of this series of alloys were studied.When the content of Co and Ni in the alloy are both 10 at.%,the best optimized soft magnetic properties are obtained after the optimized transverse magnetic field heat treatment.The initial permeability?_i=2000,the anisotropic field strength H_k=380 A/m,magnetic anisotropy constant K_u=210 J/m~3,and coercivity H_c=0.61 A/m.The core loss mechanism of Fe-based amorphous strip was studied.Soft magnetic dual-phase alloy ribbon with ultra-thin thickness of 14?m was prepared by adjusting the thermal conductivity of the cooling matrix during rapid solidification.The core loss of the ultra-thin ribbon is much lower than that of the conventional thickness of 22?m one under the same working condition,and the gain is increasing with the frequency increasing.The magnetic domain structure of the ultra-thin and conventional thickness ribbonshave been analyzed,and it is found that the fundamental reason for its good performance of high frequency core loss is that the magnetic domain structure is refined with the decrease of the thickness of the ribbon.The Fe-based FeCoNiCrSiB soft magnetic dual-phase alloys were developed.The variation law of the permeability,linearity and loss of the alloy system with Co and Ni content was studied.The magnetization mechanism of the alloy system was further explored by magnetic domain structure analysis.When the content of Co and Ni in alloy is 5 at.%and 20 at.%respectively,the optimized soft magnetic properties can be obtained by the optimized transverse magnetic field heat treatment.The initial permeability?_i=1280,the opposite field strength H_k=780 A/m,magnetic anisotropy constant K_u=500 J/m~3,coercivity H_c=0.34 A/m,and remanence B_r=1.50 mT.It is found that the alloy system has abnormal loss at 30,60 kHz after transverse magnetic field heat treatment,and it is assumed that this anomaly may be due to the resonance of the magnetic domain wall of the alloy.