Fe73.5CulNb3Si13.5B9非晶合金的晶化动力学

用差热分析(DTA)结合X射线衍射(XRD),研究了Fe73.5Cu1Nb3 Si13.5B9非晶合金的晶化动力学.结果表明:温度在0～700℃范围内,该合金的晶化相为α-Fe和Fe2B;α-Fe相晶化表观激活能为452.39 kJ/mol,Fe2B相的晶化表观激活能395.23 kJ/mol;两相在晶化初期激活能最小,随晶化量Xc的增加而迅速增大,在a-Fe的体积分数为30%～80%,Fe2B的体积分数为40%～80%时,呈现极大值.     

Fe73.5Cu1Nb3Si13.5B9软磁合金晶化处理

利用综合热分析仪测量了Fe73.5Cu1Nb3Si13.5B9晶化处理的焓变和晶化温度,并制定了不同的晶化退火工艺,利用振动样品磁强计自动测量仪对晶化处理后的试样进行了磁性能测定.研究结果表明,Fe73.5Cu1Nb3Si13.5B9软磁合金从250 ℃开始加热,经过370 ℃、470 ℃二次预热处理,在560 ℃保温1 h后,炉冷到250 ℃出炉冷却,可获得较高的软磁性能.     

Fe73.5Cu1Mo3Si13.5B9超微晶磁粉芯的研究

本文对Ｆｅ７３．５Ｃｕ１ｍＯ３Ｓｉ１３．５Ｂ９超微晶合金带制作磁粉芯的工艺进行了研究。特别对粉的粒度，成形压力，绝缘的配比以及磁粉芯的磁性能进行了深入的探讨。发现磁粉芯的性能与制粉用的微晶带材是否具有优良磁性能无关。通过调整绝缘剂量及其组分可以使磁粉芯的磁性能发生相应的变化。超微晶粉的粒度对磁粉芯的性能及频率特性起着决定的作用。     

Microstrucural characterization of gas atomized Fe73.5Si13.5B9Nb3Cu1 and Fe97Si3 alloys

Powder particles of Fe_73.5Si_13.5B₉Nb₃Cu₁ and Fe₉₇Si₃ soft magnetic alloys have been prepared by gas atomization. The gas atomized powder was microstructurally characterized and the dependence of coercivity with the composition and powder particle size investigated. As-atomized powder particles of both compositions were constituted by a bcc α-Fe (Si) solid solution. The Fe_73.5Si_13.5B₉Nb₃Cu₁ powder particles presented a grain microstructure with dendrite structure, which dendrite arms were enriched in Nb. The coercivity increased as the particle size decreased, with a minimum coercivity, of 5 Oe, measured in the Fe₉₇Si₃ alloy in the range of 50–100 μm powder particle size. The coercive fields were quite higher in the Fe_73.5Si_13.5B₉Nb₃Cu₁ than in the Fe₉₇Si₃ powder, due to the Nb addition, which produced a phase segregation that leads to a noticeable magnetic hardening.     

关于FINEMET软磁合金晶化处理的DSC分析

对Fe73 5Cu1 Nb3 Si1 3 5B9非晶合金原带和经 52 0℃等温退火处理的样品进行了DSC分析以及重复DSC分析。对非晶合金原带的激波处理样品作了对比DSC分析。将原始非晶合金原带在上述处理中的晶化速率和晶化分数作了对比并结合晶化机理进行了讨论。结果表明 ,退火晶化与激波晶化相比无论在晶化特征还是晶化动力学方面都有明显的差异     

非晶合金条带Fe73.5Cu1Nb3Si13.5B9的晶化动力学研究

采用差式扫描量热方法进行热分析实验,研究不同加热速率下非晶合金条带Fe73.5Cu1Nb3Si13.5B9的晶化动力学特性.DSC曲线的晶化温度和晶化峰值温度随着加热速率的增高而向高温方向迁移,说明合金的晶化过程表现出明显的动力学特性.建立基辛格模型,拟合动力学模型函数对结晶率的实验曲线,可以获得动力学参数值,得出晶化激活能的数值为2.89 eV.研究表明:对于Fe73.5 Cu1Nb3Si13.5B9合金,采用经验的双参数Sestak-Berggre模型能更加定量描述其晶化过程,而Johnson-Mehl-Avrami模型适宜在较低加热速率下描述.     

Fe73.5Cu1Nb3Si13.5B9纳米晶铁芯的应力退火研究

将环状Fe73．5Cu1Nb3Si13．5B9非晶合金在540℃应力退火,形成具有蠕变感生各向异性的Fe73．5Cu1Nb3Si13．5B9纳米晶铁芯。在炉冷条件下,应力退火的剩磁Br随退火时间的延长可降至0．22T;退火时间超过20min后,Br无明显改变。炉冷条件下获得的剩磁要低于空冷的剩磁。应力的作用对晶化过程中析出相的微观结构没有影响。     

纳米晶Fe_（73．5）Cu_1Nb_3Si_（13．5）B_9合金中缺陷及内应力的分布研究

用正电子湮没技术和微观磁学方法研究了纳米晶Ｆｅ_（７３．５）Ｃｕ_（１）Ｎｂ_（３）Ｓｉ_（１３．３）Ｂ_９合金结构缺陷在退火过程中的变化规律，表明晶化初期形成的界面结构只引入少量的缺陷，晶化后期由于出现大量晶界，缺陷浓度急剧上升；非晶制备过程中以及晶化时引入的准位错偶极子造成的应力场对其软磁性能有很大的影响，并可以解释在最佳退火温度的磁性行为。     

纳米晶Fe72.5Cu1Nb1.5Mo1.5V1Si13.5B9合金的磁性能

报道了新开发的纳米晶Fe725Cu1Nb15Mo15V1Si135B9合金的综合磁性能。新合金的直流起始磁导率和矫顽力水平分别达到13×104和064Am-1。在Bm=03T,f=100kHz和Bm=02T,f=200kHz条件下,铁损分别为578kW·m-3和884kW·m-3,这可与纳米晶Fe735Cu1Nb3Si135B9合金的相比,但比优良的功率MnZn铁氧体H7C4的低得多。在Bmf=(10～40)T·kHz条件下,在f=(20～6000)kHz范围内,描述了铁损、相应幅值磁导率和动态矫顽力的行为     

Fe73.5Cu1Nb3Si13.5B9非晶丝扭矩阻抗（TGI）效应的研究

本文研究了测量频率、焦耳退火处理及扭矩焦耳退火处理对Fe73.5Cu1Nb3Si13.5B9非晶丝TGI效应的影响。实验表明淬态Fe73.5Cu1Nb3Si13.5B9非晶丝TGI效应的最佳测量频率为7 MHz;对样品进行焦耳退火处理可以提高样品的阻抗变化率,测量频率为7 MHz时,焦耳退火处理的最佳电流密度为32 A/mm2,最大阻抗变化率达198%;扭矩焦耳退火处理后,样品TGI效应的非对称性随着预加扭矩的增大而增大,同时阻抗变化率峰值减小。     

Fe73.5 Cu1 Nb3 Si13.5 B9机械合金化纳米晶粉末的特种烧结及磁性能

研究了放电等离子烧结和高压烧结工艺条件对MA Fe73.5Cu1Nb3Si13.5B9纳米晶粉末的烧结块体合金的组织结构与磁性能的影响.结果表明:球磨70 h后,获得了单相a-Fe纳米晶(约9.5 rm)过饱和固溶体粉末;DSC升温曲线中,出现4个不同强度的放热峰,依次发生了纳米晶过饱和固溶体的结构弛豫、非晶晶化以及过饱和固溶体相析出等过程,且相析出过程分两个阶段完成;在p=30 MPa,t=5 min放电等离子烧结(SPS)条件下,当温度达到1 050℃后,可获得相对密度为98.9%、主相为α-Fe的纳米晶(100nm)块体合金,其中,B3=1.34 T,Hc=7.34 kA/m,在p=5.5 GPa,t=5 min条件下,当Pw=1 150 W后,可获得相对密度约99.1%、单相α-Fe纳米晶(21.4 nm)块体合金,其中,Bs=1.14 T,Hc=8.22 kA/m.     

脉冲电流退火对Fe73.5Cu1Nb3Si13.5B9合金薄带巨应力阻抗效应的影响

研究了脉冲电流退火工艺对非晶Fe73.5Cu1Nb3Si13.5B9合金薄带巨应力阻抗（GSI）效应的影响。结果表明，在外加100MPa拉应力下对非晶合金进行脉冲电流退火后，巨应力阻抗效应显著提高，并且△Z／Z最大值随退火电流密度的增加而增加，当退火电流密度为930A／mm^2时，阻抗的最大相对变化达到350％。     

退火工艺对Fe73.5Cu1Nb3Si13.5B9纳米晶带材耐腐蚀性能的影响

采用电化学方法研究了退火工艺对Fe73.5Cu1Nb3Si13.5B9纳米晶带材耐腐蚀性能的影响.用差热分析仪分析了该纳米晶带材的晶化过程,利用X射线衍射仪对经不同温度退火后的非晶带材的晶态结构进行了分析,并用恒电位法测试了样品在3.5%NaCl溶液中的耐腐蚀性能.结果表明,在3.5%NaCl溶液中,经过不同温度退火后的Fe73.5Cu1Nb3Si13.5B9纳米晶带材的耐腐蚀性能随退火温度的升高呈先增加后降低的趋势,其中530 ℃退火后的样品具有最好的耐蚀性.     

脉冲电流处理对Fe73.5Cu1Nb3Si13.5B9合金薄带GMI效应的影响

本文研究了脉冲电流处理对Fe73.5Cu1Nb3Si13.5B9合金薄带巨磁阻抗效应和脆性的影响,并与等温退火样品的巨磁阻抗效应和脆性进行对比.结果表明,经过应力脉冲电流处理后的样品,其阻抗变化率和灵敏度都显著高于无应力脉冲处理后的样品.淬态样品在9.34MPa拉应力下,经电流密度为930A/mm2的脉冲电流处理后,阻抗变化率可达到220%,灵敏度达到0.35%/A·m-1.用应力脉冲电流处理不仅可以显著提高巨磁阻抗效应,而且可以有效抑制样品长时间的等温退火带来的脆性问题.     

Fe73Cu1.5Nb3Si13.5B9淬态薄带中的巨磁阻抗效应研究

通过调高Cu在合金薄带的含量，并采用合适的甩带速度V，在FeCuNbSiB淬态薄带材料中观察到了较大的巨磁阻抗效应。甩速V=30m／s的Fe73CU1．5Nb3Si13．5B9淬态薄带在外加直流磁场H=7162A／m下，在f=300kHz时磁阻抗△Z／Zo为-22．6％。另外发现Fe3Cu1．5Nb3Si13．5B9淬态薄带中横向磁各向异性很微弱。Fe73Cu1．5Nb3Si13．589淬态薄带中AZ／Zo随磁场变化的峰值基本来源于△X／X0项的变化。在f≤16MHz的频率范围内，其峰值磁场随着频率的增加而增加。     

Effects of annealing condition and Al content on novel Fe73.5Si13.5B9Cu1Nb3-xAlx alloys

The annealing condition,Al content,and field amplitude dependences of the complex permeability for Nb-poor Finemet type alloys,Fe73.5Si13.5B9Cu1Nb3-xAlx (x=0,0.5,1.5,2.0,and 3.0),were investigated using an impedance analyzer and X-ray diffraction.The results show that different Al contents lead to different optimum annealing conditions,and the Al content exerts a distinct effect on microstructure thus resulting in a variety of real permeability value.For the samples annealed at 793 K for 0.5 h,the real permeability increases with an increase in Al content when the Al content is below 2.0 at.%; as for those annealed at 793 K for 1 h and at 813 K for 0.5 h,an overall increase in real permeability can be obtained compared to those annealed at 793 K for 0.5 h.The permeability under different field amplitudes is also studied and it is found that the relaxation frequency in the lower frequency region tends to moving toward a higher frequency with an increase in field amplitude.All these might be because of the role of Nb in the annealing process and the solubility of Al in the amorphous matrix and nanocrystallized crystallites.     

STUDY OF MECHANISM OF RQ EMBRITTLEMENT OF Fe_(73.5)Cu_1-Nb_3Si_(13.5)B_9 NANOCRYSTALLINE SOFT MAGNETIC ALLOY

Rapidly quenching embrittlement (RQE) sometimes appears in Fe73.5Cu1Nb3Si13.5B9 nanocrystalline soft magnetic alloy (FINEMET) during production process. As a re-sult of RQE the ductility of the as-quenched ribbon drops seriously. The mechanism of RQE has been elucidated in the recent works of current authors. It was believed that RQE is due to the structural relaxation but not related to a-Fe(Si) crystallization. In this paper, the high resolution TEM (HRTEM) method and image digital processing were applied to analyze the HRTEM images of two FINEMET rapidly quenched ribbons with different thicknesses in detail. In the thinner ductile sample, the ordering domains with the size of about 3nm are observed. In the thicker RQE sample, the metastable nanocrystalline domains with the size of 18nm are observed along with the structural relaxation. These domains seem to have Fe3B-like metastable phase struc-ture on nanometer scale. The result indicates that the local atomic ordering regions extend when RQE induced     

Cu clustering and Si partitioning in the early crystallization stage of an Fe73.5Si13.5B9Nb3Cu1 amorphous alloy

Solute clustering and partitioning behavior in the early crystallization stage of an Fe_73.5Si_13.5B₉Nb₃Cu₁ amorphous alloy have been studied by employing a three-dimensional atom probe (3DAP) and a high resolution electron microscope (HREM). Results from the 3DAP have clearly shown that Cu atom clusters are present in the amorphous state after annealing below the crystallization temperature. The density of these clusters is in the order of 10²⁴/m³, which is comparable to that of the α-Fe grains in the optimum nanocrystalline microstructure. In the early stage of primary crystallization, Cu clusters are in direct contact with the α-Fe nanocrystals, suggesting that the α-Fe primary particles are heterogeneously nucleated at the site of Cu clusters. In the early stage of crystallization, the concentration of Si is lower in the primary crystal than in the amorphous matrix phase, unlike in the late stage of the primary crystallization, where Si partitions into the α-Fe phase with a composition of approximately 20 at.%.     

Planar Flow Casting of Fe71Si13.5B9Nb3Cu1Al1.5Ge1 Ribbons

In this study, the planar flow casting (PFC) technique for producing wide amorphous ribbons of Fe₇₁Si_13.5B₉Nb₃Cu₁Al_1.5Ge₁ alloy is investigated. Various ribbons of the mentioned alloy were produced through applying different values of wheel speed and ejection pressure. In addition, effects of wheel speed (13, 23, and 33 m/s) on the structure, degree of amorphicity, and surface quality of the ribbons were examined. The results showed that the trends of thickness variation with increasing wheel speed and ejection pressure for Fe₇₁Si_13.5B₉Nb₃Cu₁Al_1.5Ge₁ ribbons are in good agreement with what the Bernoulli equation in fluid dynamics predicts for the PFC process. Further, based on x-ray diffraction and differential scanning calorimeter results, it was shown that the degree of amorphicity increases by increasing the wheel speed. Besides, surface roughness measurements and scanning electron microscope micrographs of the ribbons revealed that the surface quality of the prepared ribbons improved by increasing the wheel speed.