Study On Preparation And Properties Of Fe(Cu)SiBPC Amorphous/Nanocrystalline Soft Magnetic Alloys

The Fe-based amorphous/nanocrystalline alloy has a good amorphous forming ability,thermal stability,soft magnetic properties and corrosion resistance,which has a good application prospect in the field of power electronics and transformer.However,there are still some limitations in the application of transformer and ocean engineering duo to a certain gap in saturation magnetic induction between Fe-based amorphous/nanocrystalline alloy and silicon steel(about 2.0 T)and the corrosion resistance exists some defects.In this paper,Fe(Cu)-Si-B-P-C alloy ribbons were prepared by non-consumable miniature metal melting furnace and WK series high-frequency induction vacuum smelting single-roll rapid quenching strip casting machine.The phase and microstructure were characterized by X-ray diffraction(XRD)and transmission electron microscopy(TEM).The thermodynamic parameters and non-isothermal crystallization kinetics of the alloy ribbons were measured by differential scanning calorimetry(DSC).The soft magnetic properties of alloy ribbons as quenched and annealed were measured by vibrating sample magnetometer(VSM).The effects of different copper roller speeds on the amorphous formation ability,thermal stability and soft magnetic properties of Fe₈₅Si₂B_8.5P₃C₁ alloy and the kinetic mechanism of non-isothermal crystallization were studied.Fe_85-xSi₂B_8.5P_3.5C₁Cu _X(X=0,0.3,0.5,0.7,1 at.%)amorphous/nanocrystalline alloys were prepared by replacing part of Fe with Cu used to investigate the effects on the structure,soft magnetic properties and corrosion resistance of the alloys.The main work of this paper is as follows:(1)The results of X-ray diffraction patterns showed that the amorphous forming ability of Fe₈₅Si₂B_8.5P₃C₁ alloy increased with the rotation rate of copper roller,and the amorphous alloy was obtained at 40 m/s.Additionally,DSC test showed that the thermal stability of the alloy increased gradually with the copper rollers speed.VSM test showed that the coercive force decreased with the increase of the speed.(2)The non-isothermal crystallization kinetics of Fe₈₅Si₂B_8.5P₃C₁ amorphous alloy were tested and the results showed that the sensitivity of the initial temperature and peak temperature to the heating rate was related to the transformation sequence,which the first step was controlled by two-dimensional growth mechanism,while the second step was mainly controlled by three-dimensional growth mechanism,both the nucleation rate increased first and then decreased.(3)The amorphous forming ability and thermal stability of Fe_85-xSi₂B_8.5P_3.5C₁Cu _X(X=0,0.3,0.5,0.7,1 at.%)alloy ribbons can be improved by adding appropriate amount of Cu to replace Fe,and the B_S of Fe_84.3Si₂B_8.5P_3.5C₁Cu_0.7 nanocrystalline alloy increased from1.62 to 1.82 T,while the H_C decreased from 14.2 to 4.8 A/m after annealing at 480 ? for 3min.The corrosion resistance of Fe_84.3Si₂B_8.5P_3.5C₁Cu_0.7 nanocrystalline alloy before and after annealing was tested by immersed in 3.5%Na Cl solution,and it was found that there were obvious corrosion pits,spherical and acicular corrosion products on the surface of the as quenched alloy,while no corrosion pits and only a small amount of acicular corrosion products on the surface of the alloy after annealing at 480 ? for 3 min,and the surface of the alloy was smooth and flat.The results show that Fe_84.3Si₂B_8.5P₃C₁Cu_0.7amorphous/nanocrystalline alloy has good soft magnetic properties and corrosion resistance under the condition of 480 ? for 3 min.