Effect And Regulation Of Mn On Amorphous Forming Ability And Soft Magnetic Properties Of Fe-Based Amorphous Alloys

Fe-based amorphous alloys have caused extensive research by scholars with its special structural properties and excellent soft magnetic properties since its birth.They have the advantages of high permeability(?),low coercive force(Hc),low core loss and high saturation magnetic induction(BS),which are widely used in the field of power electronics.However,currently only a few alloy components can be industrialized.The first and most important technical obstacle to mass production of new alloy components is the problem of impurities in the raw materials.The influence of impurities should be analyzed from two aspects On the one hand,harmful trace elements exist in advance,which is easy to form refractory compounds that lead to heterogeneous crystallization and reduce the amorphous forming ability(GFA).On the other hand,Sn,Cr,Mn and other trace elements can effectively improve the amorphous forming ability of the alloy through microalloying,but the content needs to be strictly controlled,otherwise the soft magnetic properties will decline.There are many types of trace elements in raw materials,and their forms are variable.They also have complex interactions with their constituent elements.Therefore,it is necessary to study the influence of trace elements.In addition,it is of great significance to purify the alloy by fluxing purification.Fluxing purification is a technique commonly used in traditional metallurgy to purify materials or adjust the content of trace elements,and is very effective for improving the amorphous forming ability of alloys.Therefore,in order to explore the industrial production of Fe-based amorphous alloys,this study focuses on the influence and control of the impurity element Mn,which is common in Fe-based amorphous raw materials,on the amorphous forming ability and soft magnetic properties,and carried out the following work:Firstly,the effects of Mn on amorphous forming ability,thermodynamic properties and crystallization behavior of Fe-Si-B-P alloy system were studied.By replacing Fe,Si and B with Mn,it is found that the addition of Mn can improve the amorphous forming ability of the alloy to some extent.However,when Mn element replaces P element,it cannot improve the amorphous forming ability of Fe82B10Si5P3-xMnx(x=0.1,0.2,0.3,0.4,0.5)alloy system.When Mn is substituted for Fe,Si,B and P,the liquidus temperature(T1)decreases first and then increases.When Mn elements replace Si and B elements,T1 is low when the Mn content is 0.1 and 0.2 at.%,Which can correspond to its amorphous forming ability.When the Mn element replaces the P element,T1 increases,thereby reducing the GFA of the alloy.In addition,the addition of a small amount of Mn will move the position of the crystallization peak relatively to the left,which corresponds to the increase of the crystal plane spacing.From the perspective of atomic radius,the atomic radius relationship of five elements Mn,Fe,Si,B and P is known to be:Mn(0.135 nm)>Fe(0.124 nm)>Si(0.115 nm)>P(0.106 nm)>B(0.082 nm).Therefore,the replacement of Mn is conducive to the increase of local Fe-Fe atomic spacing,which is also consistent with the calculation results of the migration of the crystal plane of a-FeSecondly,B2O3-MnO with different mass ratios was used as binary purifier to study the effects of fluxing purification on the amorphous forming ability,thermodynamic behavior,crystallization behavior,soft magnetic properties and alloy composition of Fe85B10Ps alloy system with high Fe content.It was found that B2O3-MnO as the purification could significantly improve the amorphous forming ability of Fe85B10Ps alloy system,and the amorphous forming ability was better when B2O3:MnO=3:1.With the increase of MnO content in B2O3-MnO purification agent,curie temperature(Tc)and crystallization temperature(Tx)show a trend of first decreasing and then increasing,the value of melting point(Tm)changes little,and T1 also shows a trend of first decreasing and then increasing.When B2O3:MnO=3:1,T1 value reaches the lowest,which corresponds to the GFA result obtained by XRD.The complete crystallization annealing shows that the crystallization peak shifts to the left after purification,and the calculated lattice parameter a#is consistent with the change trend of Tc.Comprehensively compare the soft magnetic performance parameters Bs and Hc,when B2O3:MnO=3:1,the comprehensive soft magnetic performance is better.Bs and the Fe content measured by the inductively coupled plasma emission spectrometer(ICP)have the same variation pattern,because Bs largely depends on the Fe content.From the results of ICP test,B2O3-MnO as the purification can achieve the protection of P elements and have a certain effect on the contents of Fe and Mn elementsThirdly,the effect of B2O3-MgO with different mass ratios on the amorphous forming ability,thermodynamic properties,soft magnetic properties and composition changes of Fe85B10Ps alloy was studied.It was found that B2O3-MgO as the purification could significantly improve the amorphous forming ability of Fe85B10P5 alloy.Moreover,after purification by B2O3-MgO,Hc of the amorphous ribbons was within the range of 3.56-5.81 A/m,and Bs was between 1.484-1.604 T,which has good comprehensive soft magnetic properties The purification agent can achieve good protection of P element and control of Mn element.However,the content of B element is very low,only 0.812 wt.%,which will affect the amorphous forming ability of alloysFinally,on the basis of B2O3-MgO,the ternary purification B2O3-CaO-MgO was developed.With B2O3:CaO:MgO=3:0.8:0.2 as the purification,other experimental conditions were the same,and the reaction kinetics of molten slag solution was studied.It was found that some molten slag covered the surface of the parent alloy ingot after 5 minutes of purification.There is no slag on the surface after purification for 15 minutes.After purifying for 30 minutes or more,the surface of the ingot after spontaneous emulsification is very bright and the slag removal performance is good.Therefore,the change of purification time can significantly change the slag removal performance and affect the morphology of the parent alloy ingots.B2O3-CaO-MgO with different ratios was used as the purification agent for 30 minutes.The experimental results showed that the amorphous forming ability of Fe85B10P5 was effectively improved.And after B2O3-CaO-MgO purification,the Tm and T1 of the alloy have been improved,and the temperature interval ?Tm has also decreased.In addition,the Bs value of the amorphous alloy purified by B2O3-CaO-MgO is 1.616 T on average,and Hc is in the range of 5.32-7.82 A/m,which improves the comprehensive soft magnetic properties of Fe85B10P5 alloy.