Preparation And Magnetic Properties Of DC Resistant Fe-based Nanocrystalline Soft Magnetic Alloys

This paper is one of the key research and development projects of Shanxi Province,"Research on key technology of DC resistant Fe based nanocrystalline soft magnetic alloy materials"（Project No.:201803d1120124）,aiming to develop low cost DC resistant Fe-based nanocrystalline alloy.The Fe-based amorphous and nanocrystalline alloys have low coercivity,high saturation magnetic induction and permeability,and their preparation process are simple,their manufacturing cost are low,and them can be recycled.They are known as"double green material in the 21st century",and can be widely used in production and life as a magnetic material.When the magnetic core works with DC component,the traditional amorphous nanocrystalline alloys are easy to saturate and cannot work normally.Therefore,technicians began to study amorphous nanocrystalline alloys with DC resistance.However,the current DC resistant Fe-based nanocrystalline alloys have expensive Co element,which lead to increased costs.In this paper,based on the composition of Fe₇₆Si₁₃B₈Nb₂Cu₁,the composition of the alloy was designed by using Ni instead of Fe.The developed composition was subjected to conventional heat treatment and transverse magnetic field heat treatment,and the ribbons with different thickness were designed,and the best magnetic properties were obtained.The main research contents and conclusions are as follows:（1）The composition of Fe_76-xNi_xSi₁₃B₈Nb₂Cu₁（x=0,3,5,7,10,12）was developed.The experimental results show that the initial permeability of the alloy decreases gradually with the increase of Ni content,from 62.120 k of x=0 to 9.948 k of x=12.The anisotropic field strength of nanocrystalline alloys are less than 50 A/m;The optimum grain size after heat treatment is about 10-15 nm;The minimum loss of Fe₇₃Ni₃Si₁₃B₈Nb₂Cu₁nanocrystalline alloy is 74.62 W/kg at 0.2 T/100 kHz.（2）The effect of transverse magnetic field heat treatment on the properties of the ribbons was studied.After transverse magnetic field heat treatment,the initial permeability of Fe₆₄Ni₁₂Si₁₃B₈Nb₂Cu₁alloy is 3.247 K,the coercivity is 4.217 A/m,the loss is 27.14 W/kg at0.2 T/100 kHz,and the anisotropic field strength is H_k=250 A/m.The soft magnetic alloys with low permeability,low coercivity and low loss are obtained（3）The Fe₆₉Ni₇Si₁₃B₈Nb₂Cu₁alloy with excellent comprehensive magnetic properties was selected.By adjusting the rotating speed of the copper roller,20 and 24μm thick ribbons were ejected.The transverse magnetic field heat treatment was carried out by winding the ribbons into 20×14×10（outer diameter×inner diameter×height,mm）specification.The influence of ribbon thickness on the soft magnetic properties of nanocrystalline core was studied.The experimental results show that the loss of thin ribbon is lower than that of thick ribbon at the same frequency and magnetic field intensity.