Preparation And Soft Magnetic Properties Of Fe-B-P Amorphous Alloy System With High Iron Content

The close-packed and lattice-free microstructure of amorphous alloys gives them excellent performance:high strength,hardness,excellent corrosion resistance,and minimal anisotropy as soft magnetic materials.These excellent properties make Fe-based amorphous alloys rapidly become stars in soft magnetic materials,which respond to the changes of external magnetic field rapidly,and can obtain high magnetic induction intensity with low loss.In recent decades,the development and application of iron-based amorphous alloys have become extremely active and important.Comparing Fe-based amorphous alloy with silicon steel which is the main competitor in the market,the coercivity of amorphous alloy has incomparable advantages.However,the confinement of lattice structure and iron content in dense stack also restricts the saturated magnetic induction(Bs)of Fe-based amorphous alloy(<1.72 T),which is much lower than the Bs of silicon steel(2 T).But it also reminds us that there is still big upgrade space for improvement of the saturated magnetic induction strength of Fe-based amorphous alloys.In order to develop high-performance Fe-based amorphous alloys and promote their industrial production,the following aspects are discussed in this paper:Firstly,the dependence of Bs on composition was studied.Based on the rigid band model and charge transfer model,the theoretical values of saturated magnetic induction(Bs,cal)were calculated on the basis of the concentration of each component in Fe-based amorphous alloy.It was found that the linear relationship between Bs,cal and Bs measured by experiments was satisfied.The results show that Bs of Fe-based amorphous alloys with Fe content less than 75at.%are in good agreement with those Bs.cal calculated by electron transfer model,which reveals that when the iron content is below 75at.%,the fluctuation of Bs is mainly caused by the transfer of free electrons between metal atoms and the 3d electronic layer of Fe atoms.When Fe content is higher than 75at.%,the change of Bs can not only be explained by the effect of composition but also the exchange coupling interaction reflected by the Bethe-Slater curve.Then,an approximate equation considering both the effects of electron transfer and exchange coupling interaction was established.The fitting degree and linear correlation of the equation were much better than those of the previous models.It can be used as a reference for the design of Fe-based amorphous alloys with required BS.Secondly,the effect of Mn substitution for Si on amorphous forming ability,soft magnetic properties and morphology of Fe-B-P-Si alloy was studied by designing alloy composition Fe83B10P5Si2-xMnx.The experimental results show that the amorphous forming ability of Fe83B10P5Si2-xMnx alloy increases first and then decreases with the increase of Mn content.It is noteworthy that the addition of trace antiferromagnetic element Mn(less than 0.3at.%)can enhance the Bs of the alloy.In this experiment,0.1 at.%Mn has the best effect on the Bs,which makes the Bs of the alloy increases from 1.54 T(Fe83B10P5Si2)to 1.6T.The experimental results show that trace metal impurities have remarkable effects on the properties of Fe-based amorphous alloys,which provides a reference for controlling the quantities of impurity elements in the preparation of amorphous alloys by using low-purity raw materials.Finally,in order to produce P-containing Fe-based amorphous alloys under industrial conditions,which is low vacuum and have multiple impurities,the fluxing agency were developed.In this work,Fe-B-P-Si alloys with excellent comprehensive properties is selected as the target component for fluxing agency development.Different basicities of fluxing agency were obtained by adjusting the mass ratio between B2O3 and different oxides.The effect of fluxing agency was evaluated from the formation ability of amorphous ribbons,slag removal and ingot-morphology.The basicity of the fluxing agency system with ideal purifying effect is as follows:for B2O3-MgO,R= 0.25-0.33;for B2O3-MnO,R=0.33?1;for B2O3-SJ101,R= 0.44.