Behavior of Medium-frequency Core Loss in Fe-based Nanocrystalline Soft Magnetic Alloys

The dependences of the power loss per cycle on frequency have been investigated in the ranges of 100 Hz<= f<=25000 Hz and 0.1 T< =Bm <=1.0 T for three main original magnetic states in five sorts of Fe-based nanocrystalline soft magnetic alloys. The measured and calculated results showed that the total power loss per cycle clearly exhibited a nonlinear behavior in the range below 3 kHz～5 kHz depending on both the magnetic state and the value of Dm, whereas it showed a quasi-linear behavior above this range. The total loss was decomposed into hysteresis loss, classical eddy current loss and excess loss, the obvious nonlinear behavior has been confirmed to be completely determined by the dependence of the excess loss on frequency. It has been indicated that the change rate of the excess loss per cycle with respect to frequency sharp decreases with increasing frequency in the range below about 3 kHz～5 kHz, wherease the rate of change slowly varies above this range, thus leading to the quasilinear behavior of the total loss per cycle. In this paper, some linear expressions of the total loss per cycle has been given in a wider medium-frequency segment, which can be used for roughly estimating the total loss.

General Properties of Low-frequency Power Losses in Fe-based Nanocrystalline Soft Magnetic Alloys

The dependences of the power loss per cycle on frequency f and amplitude flux density Bm have been investigated for the three main original magnetic states in five sorts of Fe-based nanocrystalline soft magnetic alloys in the ranges of 10 Hz<=f<=1000 Hz and 0.4 T<= Bm <=1.0 T. The total loss P is decomposed into the sum of the hysteresis loss Physt, the classical eddy current loss Pel and the excess loss Pexc. Physt has been found to be proportional to Bm^2 and f. The behavior of Pexc/f vs f being equivalent to P/f vs f clearly exhibits nonlinearity in the range not more than about 120 Hz, whereas the behavior of P/f vs f roughly shows linearity in the range far above 100 Hz and not more than 1000 Hz. In the range up to 1000 Hz, Physt is dominant in the original high permeability state and the state of low residual flux density, whereas Pexc in the state of high residual flux density is dominant in the wider range above about 100 Hz. The framework of the statistical theory of power loss has been used for representing the behavior of Pexc/f vs f. It has been found that the number n of the simultaneously active 'Magnetic Objects' linearly varies as n = n0 + Hexc/H0 as a function of the dynamic field Hexc in the range below about 120 Hz, whereas n approximately follows a law of the form n = n0 + (Hexc/H0)^m with 1 < m < 2 in the range far above 100 Hz and not more than 1000 Hz. The values of the field HO in principle related to the microstructure and the domain structure have been calculated for the three states.

Effect of the Partial Substitution of V for Nb on the Magnetic Properties of Fe-based Nanocrystalline Alloy

The variation of the magnetic properties of the nanocrystalline alloys for the partial substitution of V for Nb with crystallizing treatment temperature and time was investigated. The variation law of the magnetic properties with the annealing temperature and time is essentially the same. The magnetic properties of the Fe-based nanocrystalline alloys for the partial substitution of V for Nb reduce, and the crystallizing treatment temperature of the alloys increases. The optimum properties of Fe74Cu1Nb3Si13B9 nanocrystalline alloys crystallized at 550℃x60 min are μ0=9.2xl0^4, μm=54.8xl0^4, Hc=1.14 A/m and Bs=1.26 T. The best properties for Fe74Cu1Nb3Si13B9 alloys annealed at 560℃x60 min are μ0=8.79x10^4, μm=50.18xl0^4, Hc=1.26 A/m and Bs=1.24 T.

Decomposition of pre-existing Au-P clusters induced in situ a-Fe grains uniformization in Fe-P-based nanocrystalline alloys

In Fe-based amorphous-/nanocrystalline ribbons,the uniformization and refinement of a-Fe grains are key aspects for optimizing their soft magnetic and mechanical properties.Herein,the Fe-P-C-B nanocrystalline alloy system was selected for investigation.We produced as-spun ribbons with pre-existing nanocrystals through melt-quenching and then obtained a well-distributed a-Fe nanocrystalline structure through annealing below the first crystallization onset temperature(633 K)resulting in excellent magnetic properties(saturation magnetization of 1.65 T and coercivity of 1.6 A·m^(-1))ultra-wide annealing temperature window(from 613 to 733 K),and extremely high annealing stability(up to 480 min at 633 K).Furthermore,we propose a new in situ two-step mechanism for the uniformization of a-Fe nanocrystals,which is separately induced by the decomposition of the Au-P clusters and the pre-existing a-Fe nanocrystals during annealing.This work underscores the crucial significance of micro-alloying via metastable clusters primarily influenced by metal-phosphide interactions in the process of refining a-Fe nanocrystals.Furthermore,i introduces a new principle for optimizing the comprehensive properties of Fe-based amorphous/nanocrystalline alloys.

Formation and crystallization behavior of Fe-based amorphous precursors with pre-existingα-Fe nanoparticles-Structure and magnetic properties of high-Cu-content Fe-Si-B-Cu-Nb nanocrystalline alloys

Structure,crystallization behavior,and magnetic properties of as-quenched and annealed Fe_(81.3)Si_(4)O_(13)Cu_(1.7)(Cu1.7)alloy ribbons and effects of Nb alloying have been studied.Three-dimensional atom probe and transmission electron microscopy analyses reveal that high-number-density Cu-clusters and Pre-existing Nano-sized a-Fe Particles(PN-a-Fe)are coexistence in the melt-spun Cu1.7 amorphous matrix,and the PN-α-Fe form by manners of one-direction adjoining and enveloping the Cu-clusters.Two-step crystallization behavior associated with growth of the PN-a-Fe and subsequent nucleation and growth of newly-formedα-Fe is found in the primary crystallization stage of the Cu1.7 alloy.The number densities of the Cu-clusters and PN-a-Fe in melt-spun Fe8_(1.3-x)Si_(4)B_(13)Cu_(1.7)Nb_(x)alloys are gradually reduced with enriching of Nb,and a fully amorphous structure forms at 4 at.%Nb,although smaller Cu-clusters still exist.After annealing,2 at.%Nb coarsens the average size(D_(α-F)e)of theα-Fe grains from 14.0 nm of the Nb-free alloy to 21.6 nm,and 4 at.%Nb refines the D_(α-Fe)to 8.9 nm.The mechanisms of theα-Fe nucleation and growth during quenching and annealing for the alloys with large quantities of PN-α-Fe as well as after Nb alloying have been discussed,and an annealing-induced oc-Fe growth mechanism in term of the barrier co-contributed by competitive growth among the PN-a-Fe and diffusion-suppression effect of Nb atoms has been proposed.A coercivity(HC)αDα-Fe^(3)correlation has been found for the nanocrystalline alloys,and the permeability is inverse with the H_(C).

Reduction of High-Frequency Core Loss of a Fe_(77.2)Si_(11)B_(8.5)Cu_(0.8)Nb_(2.5)Soft Magnetic Nanocrystalline Alloy by Minor Alloying

Enhancing saturation magnetic flux density(Bs)while reducing high-frequency core loss in Finemet-type nanocrystalline alloys is of great significance in achieving the miniaturization,high-frequency,and energy-saving of modern power electronic devices.In this work,we first designed a high-Bs Fe_(77.2)Si_(11)B_(8.5)Cu_(0.8)Nb_(2.5)alloy by appropriately reducing the non-magnetic elements in typical Finemet nanocrystalline alloys,and subsequently alloyed 2 at%Co,Al,and Mo,respectively.The effects of alloying elements on structure and static and high-frequency magnetic properties were studied.The results reveal that,alloying Al or Mo reduces the averageα-Fe grain size(Dα-Fe)in the nanocrystalline alloys,while Co exhibits a slight influence.The added Al or Mo results in decreases in both the Bs and coercivity(Hc)of the nanocrystalline alloys,whereas Co increases the Bs without changing Hc,and meanwhile,all alloying elements show minimal effects on effective permeability(μe).Furthermore,the addition of Co,Al,or Mo lowers the core loss(Pcv)at 0.2 T/100 kHz of the based nanocrystalline alloy with reductions of 10.9%,29.6%,and 26.8%,respectively.A Fe_(75.2)Si_(11)B_(8.5)Cu_(0.8)Nb_(2.5)Al_(2)nanocrystalline alloy exhibits outstanding soft magnetic properties with Bs,Hc,μe at 10 kHz and 100 kHz,and Pcv at 0.2 T/100 kHz of 1.34 T,0.8 A/m,27,400,18,000,and 350 kW/m3,respectively.The reduction in Pcv is primarily attributed to the decreased eddy current losses,originating from the increased electrical resistivity by elements alloying.

Preparation and Study of the Crystallization Behavior of the Fe87Zr7B5-x Nanocristalline Soft-Magnetic Alloys

A series of materials of composition Fe87Zr7B6,Fe87Zr7B5Ag1,Fe87Zr7B5Cu1 have been prepared by the melt spinning method for different cooling speed to get completely or partly amorphous ribbons.It is proved that the crystallization process is composed of 2 steps.The first step is the precipitation of&-Fe only and the second step is the phase separation of&-Fe,Fe2Zr and Fe2B.All our own made materials have been used in the library monitoring system.Most of them showed a capability of triggling the alarm of the system.The triggling sensitivity at different positions and different sample geometry were investigated and the physical mechanisms were analyzed.

铁基非晶纳米晶合金带材滚剪加工过程分析

在生产现场采用跟踪统计方法,归纳分析铁基非晶纳米晶合金带材滚剪加工过程以及滚剪刀耐用度、刀具刃磨等问题,统计分析不同宽度滚剪刀的加工情况发现,滚剪刀有效工作时间比率为65%~88%,平均有效工作时间比率为76.1%,有效工作时间不稳定;滚剪刀剪切行程处于3700~4200m之间,平均剪切行程为3839.74m,刀具耐用度存在较大差异,剪切宽度越大滚剪刀耐用度越长;滚剪刀刃磨时刀具径向去除量在80~150μm之间,平均刃磨去除量为106μm,刀具刃磨工艺对刀具耐用度有决定性影响。最后针对滚剪刀磨损检测问题,提出采用声发射信号对滚剪刀状态进行在线检测的技术方案。

Direct synthesis of Fe-Si-B-C-Cu nanocrystalline alloys with superior soft magnetic properties and ductile by melt-spinning

Structure,magnetic properties and ductile of melt-spun Fe_(83-x)Si_(4)B_(13-y)C_(y)Cu_(x)(x=0-1.7;y=0-8)alloys were investigated.The addition of 1.7 at.%Cu in a Fe_(83)Si_(4)B_(13) amorphous alloy generates abundantα-Fe crystals by providing nucleation sites,and further C doping promotes the growth of the crystals by suitable turning amorphous-forming ability,hence they increase saturation magnetic flux density(B_(s))and slightly worse magnetic softness of the as-spun alloys.The as-spun Fe_(81.3)Si_(4)B_(7)C_(6)Cu_(1.7) alloy possesses a combined structure of a fully amorphous layer in wheel side surface and predominating nanocrystalline structure with gradually enlargedα-Fe crystal,whose average size and volume fraction are determined as about 12 nm and 32%,respectively,therefore superior soft magnetic properties and ductile with a high B_(s)of 1.74 T,coercivity(H_(c))of 32.7 A/m,effective permeability(μ_(e),at 1 kHz)of 3200 and high relatively strain at fracture(ε_(f))of 3.61%can be achieved directly in this alloy by only using melt-spinning.The annealing at 578 K releases internal stress,promotes the growth of theα-Fe crystals and remains the amorphous layer of the Fe_(81.3)Si_(4)B_(7)C_(6)Cu_(1.7) alloy,then improves the soft magnetic properties and maintains the superior ductile with increasing the B_(s)andμ_(e)to 1.80 T and 14,100,respectively,lowering the H_(c)to9.4 A/m and slightly reducing theε_(f)to 2.39%.The combination of superior soft magnetic properties and ductile and simplified synthesis process entitles the Fe-Si-B-C-Cu nanocrystalline alloys great potentials in high performance electromagnetic applications.

Microstructure and magnetic properties of Fe81.3Si4B13Cu1.7 nanocrystalline alloys with minor Nb addition

The amorphous matrix contAlning dispersive high number density （Na） α-Fe nuclei with average grAln sizes （D） of 4.3-6.2 nm was formed in the melt-spun Fe81.3-xSi4B13Cu1.7Nbx （x = 0-2） alloys, and the Nd and D values reduce with increase in the Nb content. The fine nanocrystalline structure with α-Fe grAlns of 14.0-21.6 nm in size was obtAlned for the annealed alloys, which showed high saturation magnetic flux density of 1.60-1.77 T and low coercivity （He） of 7.1-17.0 A/m. Addition of minor Nb significantly expands the optimum annealing temperature range for obtAlning good soft magnetic properties, while coarsens the α-Fe grAlns, leading to a slight increase in the Hc. The mechanism of the effect of Cu and Nb elements on the structure and magnetic properties was discussed in terms of the formation and growth of the α-Fe nuclei of the alloys.

Effects of Ribbon Thickness on Structure and Soft Magnetic Properties of a High-Cu-Content FeBCuNb Nanocrystalline Alloy

The effects of ribbon thickness(t)on the structure and magnetic properties of a Fe_(82.3)B_(13)Cu_(1.7)Nb_(3) alloy in melt-spun and annealed states have been investigated.Increasing the t from 15 to 23μm changes the structure of the melt-spun ribbons from a single amorphous phase to a composite with denseα-Fe nanograins embedded in the amorphous matrix.The grain size(D_(α-Fe))of theα-Fe near the free surface of the ribbon is about 6.7 nm,and it gradually decreases along the cross section toward the wheel-contacted surface.Further increasing the t to 32μm coarsens the D_(α-Fe) near the free surface to 15.2 nm and aggravates the D_(α-Fe) ramp along the cross section.After annealing,the ribbon with t=15μm has relatively largeα-Fe grains with D_(α-Fe)>30 nm,while the thicker ribbons possessing the pre-existing nanograins form a finer nanostructure with D_(α-Fe)<16 nm.The structural uniformity of the ribbon with t=23μm is better than that of the ribbon with t=32μm.The annealed ribbons with t=23 and 32μm possess superior soft magnetic properties to the ribbon with t=15μm.The ribbon with t=23μm exhibits a high saturation magnetic flux density of 1.68 T,low coercivity of 9.6 A/m,and high effective permeability at 1 kHz of 15,000.The ribbon with t=32μm has a slightly larger coercivity due to the lower structural uniformity.The formation mechanism of the fine nanostructure for the ribbons with suitable t has been discussed in terms of the competitive growth effect among the pre-existingα-Fe nanograins.

FePCCu nanocrystalline alloys with excellent soft magnetic properties

The effect of Cu addition on crystallization behavior and soft magnetic properties of Fe84-xP10C6Cux （x = 0-1.15） alloys was investigated. Low-cost FePCCu nanocrystalline alloys dispersed with ct-Fe phase with an average grain size of 15-35 nm were obtained by appropriately annealing the melt-spun ribbons at 683 K for 5 min. The Fe83.25P10C6Cu0.75 nanocrystalline alloy ex- hibits a high Bs of 1.65 T, low Hc of 3.3 A/m and high μc at 1 kHz of 21 100, which is superior to the traditional FePC soft magnetic alloys. The core loss is as low as 0.32 W/kg at 1.0 T and 50 Hz, which is 60% that of nonoriented Fe 6.5 mass% Si-steel. It is encouraging to synthesize this Fe-based nanocrystalline alloy with excellent soft-magnetic properties even using commercially industry-grade raw materials, which is promising for the future industrial applications.

铁基纳米晶合金带材叠层剪切加工特性研究

针对铁基纳米晶合金带材剪切加工过程,探究了不同剪切层数对纳米晶合金带材剪切加工特性的影响,分析了叠层剪切后带材断面和截面形貌特征以及磁畴结构变化情况,并归纳出剪切速度和径向重叠量对纳米晶合金带材叠层剪切质量的影响规律。结果表明,不同剪切层数得到的带材断面形貌具有差异性,单层剪切断面形貌以剪切断裂区为主,并形成小量毛刺,磁畴排列规律;叠层剪切断面发生不同程度损伤,如材料堆积、局部剥落、磁畴紊乱等。叠层纳米晶合金带材剪切加工能够提高效率,但会导致毛刺增大、断面完整性下降。随着剪切速度的增加,各层纳米晶合金带材毛刺高度减小,断面完整性增大,纳米晶合金带材剪切毛刺高度随径向重叠量的增大呈先增大后减小的趋势,而断面完整性则逐渐变差。

基于铁基纳米晶合金薄带的压磁式压力传感器的研究

对一种利用Fe基纳米晶软磁合金薄带作为敏感材料的新型压磁式压力传感器进行了可行性研究。介绍了该传感器的结构、工作原理、输出特性以及主要参数的选择。然后通过试验,分析了传感器的静态特性以及温度变化对输出的影响。试验结果表明,该传感器的最大线性误差为2.22%(满量程),最大不重复误差为0.97%(满量程),未经放大的最大灵敏度为0.2073μV/Pa,零点每摄氏度温漂小于1.22%(满量程)。该传感器具有结构简单、工作可靠、成本低廉,以及测压范围宽等优点。

厚度对纳米晶软磁合金带材自由面结构的影响

为了可以更好地了解厚度对纳米晶软磁合金带材结构的影响,需要通过试验,采用熔炼、喷烤等工艺制备带材,熔炼温度为50~100℃,压力为0.3~0.8 MPa,通过SEM、AFM分析带材自由面结构。基于此,文章针对厚度对纳米晶软磁合金带材结构的影响展开试验,通过加热融化提纯形式,对实际影响展开分析。

铁基纳米晶合金带材叠层剪切加工特性研究

铁基纳米晶合金带材叠层剪切加工质量与层数、剪切速度等有直接的关系,因此,在对铁基纳米晶合金带材叠层剪切加工过程进行分析中,则需要从剪切速度、毛刺控制等角度进行完善,从而实现铁基纳米晶合金带材叠层剪切加工水平的进一步提升。在分析铁基纳米晶合金带材叠层剪切加工工艺流程的基础上,从铁基纳米晶合金带材叠层剪切加工流程以及影响因素的角度进行分析,并针对剪切速度、剪切层数与铁基纳米晶合金带材磁畴结构、加工质量的变化关系进行分析,旨在提高铁基纳米晶合金带材叠层剪切加工的综合水平。

The influence of Si substitution on soft magnetic properties and crystallization behavior in Fe_(83)B_(10)C_(6-x)Si_xCu_1 alloy system

In this study, the soft magnetic properties and crystallization behavior of Fes3B10C6-xSixCul （x=0-4） nanocrystalline alloys prepared by annealing the melt-spun amorphous ribbons have been investigated. It is found that in the Fe83B10C6-xSixCU1 alloy system, the coercivity （Hc） decreases slightly with increasing Si addition and exhibits a minimum value with composition of x = 2, while the effective permeability （Ue） shows an opposite variation trend. The saturation magnetic flux density （Bs） shows a slightly decreasing trend owing to the decreasing volume fraction of nanocrystalline phase. The Fe83B10CaSi2Cu1 nanocrystalline alloy exhibits excellent soft magnetic properties with a high Bs of 1.78 T, high ue of 13 600 and low Hc of 4 A/m.