Exploration And Processability Of Fe(Ni)SiB(PC) Amorphous Soft Magnetic Alloy With High-B_s

Amorphous alloys,the atomic arrangement with short-range order and without the long-range order,can be regarded as a super-cold liquid with high viscosity.Compared with crystalline alloys,the amorphous alloys present significant difference in physical,chemical and mechanical properties,many unique properties,including mechanical,thermal,light,electric,magnetic and chemical properties that crystal materials do not have.In recent decades,amorphous soft magnetic alloys have been one of the hotspots in the field of materials,especially the research and the application of amorphous soft magnetic ribbon with high-B_s.However,the commercial amorphous soft magnetic alloys have the shortcomings such as low Bs,poor thermal stability and poor amorphous forming ability.Therefore,it is necessary to study its influence mechanism and develop a new type of high performance amorphous soft magnetic alloy.At the same time,the processability,oxidation resistance and corrosion resistance of the new amorphous soft magnetic alloy play an important role in ribbon production,heat treatment and later application.Therefore it is also necessary to carry out systematic research and develop the matching processes both for ribbon production and heat treatment.In this paper,based on the popular high-Bs amorphous soft magnetic alloy without large atomic radius element,the influence of alloy composition on glass-forming ability and soft magnetic properties is studied by using single roll melt-spun method and vibratory magnetometer,and a new type of amorphous alloy with excellent soft magnetic properties is developed by adjusting the alloy composition.The technological properties of FeSiB,FeSiBPC and FeNiSiBP alloys with high Fe content were systematically evaluated,by which the melt purification process and an new heat treatment process were developed.The main developments are as follows:?1?Fe?SiBPC?alloy system,Fe can not only form a combination of large,medium and small atoms with metalloid elements such as Si,P,C and B,but also have a large negative mixing enthalpy between all those metalloid elements,which meets the formation conditions of alloys with high amorphous forming ability.In addition,by excluding other metal elements with large atomic radius,the content of Fe in alloy composition can be increased while giving full play to all kinds of metalloid elements to improve the glass-forming ability of alloy,thus giving the possibility for obtaining amorphous alloy composition with high B_s.By comparing the glass-forming ability of Fe₈₃B₁₇,Fe₈₃B₁₅Si₂,Fe₈₃B₁₄Si₂C₁,Fe₈₃B₁₂Si₂P₃Fe₈₃B₁₁Si₂P₃C₁ alloys,it is found that the more complex the alloy system,the higher the glass-forming ability.The addition of P and C can improve the stability of Fe2B phase.The addition of Si can change the primary crystal phase from Fe₂B phase to competitively precipitated?-Fe phase.?2?In the process of preparing Fe₈₃B₁₁P₃Si₂C₁ glassy ribbon with high-B_s from industrial raw materials,it is found that impurities lead to the formation of crystallization layer on the free surface of as-spun ribbon,which seriously aggravates the soft magnetic properties.In order to solve this problem,a melt purifier and slag remover from the mixture of B₂O₃ and CaO was developed,which can not only effectively reduce the linear speed of the wheel during the ribbon preparation,improve the glass-forming ability of the alloy,inhibit the crystallization of the free surface of the ribbon,but also greatly improve the soft magnetic properties,including increasing permeability and reducing coercivity.The purification mechanism is that the purifier absorbs high melting point impurities and avoids the heterogeneous nucleation of crystal phase.However,it is worth pointing out that the saturated magnetic flux density,B_s,of the ribbon prepared by the purified alloy decreases from 1.67 T to 1.65 T.?3?Based on the FeSiBP alloy with higher glass-forming ability,a?Fe1-x Nix?78Si4B13P5?x=0-0.8?alloy with high glass-forming ability and excellent magnetic properties was developed by adding of Ni.Both the melting point and the number of solidification precipitation peaks of the alloys are reduced and the composition is closer to the eutectic point with Ni addition.Which improves the glass-forming ability,and can meet the requirements of glassy ribbon production.At the same time,the large supercooled liquid zone interval and high thermal stability of the glassy alloys make them meet the requirements of heat treatment and have good technological properties.The(Fe_1-xNi_x)₇₈Si₄B₁₃P₅?x=0-0.8?alloy has excellent magnetic properties,B_s of 0.65-1.57 T,H_c of only 2.1-0.7 A/m,and magnetic permeability of 9-25×10³.The magnetic properties of the alloys go beyond the current commercial FeNi-based amorphous alloy.?4?The addition of P significantly reduces the oxidation resistance of FeSiBP alloys,and reduces the surface oxidation and overall oxidation temperature as well as the stable temperature range of the surface oxide layer.Oxidation causes a significant discoloration of the surface of the high P content FeSiBP alloy,and causes a significant decrease in magnetic properties,maintaining a significant increase in coercivity and a decrease in magnetic permeability.Oxidation also causes blurring of the magnetic domains on the surface of the ribbon,as well as strong magnetic domain pinning.The heat treatment of the hydrogen-containing atmosphere can effectively reduce the surface oxide layer of the FeSiBP alloys,restore the metal color of the surface of the severely oxidized ribbon,and greatly improve the soft magnetic properties of the ribbon,which is an effective method to solve the oxidation problem of glassy ribbon with high P content during heat treatment.