The Effects Of Magnetic Field Treatment On Soft Magnetic Properties Of Amorphous Powder Core

Because of disordered close-packed atomic structure ofsoft magnetic amorphous alloys,compared with the traditional crystalline metallic material,amorphous alloys achieve high permeability,saturation magnetic flux density,low coercivity,low core loss and so on.With the development of miniaturization,lightweight,high efficiency and high frequency in electronics industry,Fe-based amorphous alloy ribbons fail toexert excellent performance in these conditions.However,the amorphous powder milled by amorphous ribbon can meet the need of electronics industry.Nowadays,amorphous powder milled by ribbon has irregular shape,so it is hard to be coated fully and itspowder core has unsatisfactoryperformance and stability.The improvement of performance about amorphous powder core is important to theory research and fabrication in industry.Magnetic field annealing is one kind of simple method to improve the structure and properties of materials.Though there are many investigation about the effect of magnetic field annealing on amorphous ribbon,there is little research on amorphous powder core.According to the existing problem of powder core,this paper uses the common composition Fe78Si9B13 as research object.After we make the powder and powder core annealed by magnetic field,we investigate the soft magnetic properties and magnetic domain structure,to perfect the effect of magnetic field and make reference for application.The conclusions of this paper were as follows:（1）There are serious residual stresses in the amorphous magnetic powder at the process of ribbon quenched and ball milled.We made the powder pre-annealed in magnetic field and vacuum.Then the powder was made into powder core by coating,passivation and cold pressing.We found that saturation magnetic flux density（B_s）,permeability（μ）and core loss(P_cv)were greatly improved.The magnetic domain structure was observed by magnetic force microscope（MFM）.The effects of pre-annealed powder after passivatedon theperformance were also researched.（2）The paper researched the effect of transverse magnetic field annealing on the amorphous powder core about the soft magnetic properties.The morphology of different treatment processes was observed by scanning electronic microstropy（SEM）.When the intensity of magnetic field is stable,we discuss the effect of annealing temperature on soft magnetic properties and phase structure.（3）The paper researched the effect of longitude magnetic field annealing on the amorphous powder core about the soft magnetic properties.We researched the performance of annealed amorphous powder core,such as,complex permeability,core loss,quality factor,loss factor,DC bias property.The phase structure and micro morphologywere checked.Becaues of large demagnetizing field in plate powder,this paper also researched spherical powder.With the increase of magnetic field intensity,the properties of amorphous powder core were improved and the best performanceshifts to higher frequency.