Microwave absorption properties of FeSiBNbCu glass-covered amorphous wires

Coaxially dielectric samples consisting of different packing ratios of glass-covered Fe73.5Si13.5B9Nb3Cu1 amorphous wires embedded in a paraffin wax matrix were fabricated, and the influence of short-wire packing ratio (3%-9% in mass fraction) and thickness (1-7 mm) on the microwave absorption properties was systematically investigated in microwave frequency range of 2-18 GHz. X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and scalar network analyzer (SNA) were used for characterizing microstructure and evaluating microwave absorption properties. Experimental results show the significant frequency (6-18 GHz) dependence of the complex relative permeability and permittivity. The reflection loss (RL) with different thickness and short-wire packing ratio reveals that the composite sample containing 7% exhibits better microwave absorption behavior with its minimum value of RL reaching-34 dB in thickness of 3 mm at 14 GHz. Therefore, it is significantly useful to develop microwire-dielectric materials with much wider absorption band for microwave absorption applications.

Giant Magneto-Impedance Effect in Amorphous and Current Annealed Fe73.5Cu1Nb3Si13.5B9 Wire

The magneto-impedance(MI) effect in amorphous and current annealed Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9 wires has been measured to investigate the influence of DC annealing,highcurrent-density electropulsing annealing and tensile stress applied during annealing process.The results showed that the MI of DC annealed sample exhibits a sharp maximum.The Maximum MI ratio of 60%was observed in the sample of high-current-density electropulsing annealed under applied tensile stress.

Magnetic properties and promising cryogenic magneto-caloric performances of Gd_(20)Ho_(20)Tm_(20)Cu_(20)Ni_(20) amorphous ribbons

The magnetic cooling utilizing magneto-caloric effect is recognized as promising energy efficiency and environmentally friendly technology.Here we report a systematical study on the microstructures,magnetic properties and cryogenic magneto-caloric performances of the Gd_(20)Ho_(20)Tm_(20)Cu_(20)Ni_(20) amorphous ribbons.It is found that the ribbons reveal a second-order phase transition and are accompanied by a table-shaped magneto-caloric effect.The calculated magneticentropy-change maximum |ΔSM|,temperature averaged entropy change(i.e.,TEC(10)),and refrigerant capacity reach 13.9 J/kg·K,13.84 J/kg-K and 740 J/kg with magnetic field change of 0-7 T,respectively,indicating that the present Gd_(20)Ho_(20)Tm_(20)Cu_(20)Ni_(20) amorphous ribbons are good candidates for magnetic cooling.

Giant Stress-impedance Effect in Amorphous and Current Annealed Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9 Ribbons

The giant stress-impedance (GSI) effect in amorphous and current annealed Fe73.5Cu1Nb3Si13.5B9 ribbons has been investigated. The results showed that the GSI effect changed drastically with annealing techniques and the maximum stress impedance ratio of 350% was obtained after optimal conditions of current annealing. The behaviors of the stress impedance vary with densities of annealing current and the stress longitudinally applied during current annealing. The maximum change of stress impedance existed in the sample annealed by high-current-density electropulsing under applied stress of 100 MPa.

Nanoscale Morphology in Tensile Fracture of a Brittle Amorphous Ribbon

The paper reports on the observation of nanoscale morphology on the tensile fracture surface of a brittle amorphous Fe-based ribbon. The formation of nanoscale damage cavity structure is a main characteristic morphology on the fracture surfaces. Approaching the ribbon boundary, these damage cavities assemble and form the nanoscale periodic corrugations, which are neither Wallner lines nor crack front waves. The periodic corrugations result from the interactions between the reflected elastic waves by the boundaries of amorphous ribbon and the stress fields of the crack tip.

Frequency dependence of magnetization and giant magneto impedance effect of amorphous wires

The frequency dependence of magnetization process and giant magneto impedance （GMI） effect of Co-rich melt-extracted amorphous wires was studied by Kerr effect and impedance analyzer, respectively. It is demonstrated that the transverse Kerr intensity and the corresponding GMI response increase with increasing frequency, which contributes to the upgraded skin effect. However, the skin depth has a slothful trend with frequency when it is up to the megahertz range, which gives rise to the transformation of magnetization. The process is much more sensitive to the direct current magnetic field and the sensitive change of the circular permeability, and GMI response is observed as its consequence. This proves that the evolution of circumferential magnetization and the corresponding permeability with the direct current magnetic field is the essence of GMI response, and a much more sensitive magnetization promises a better GMI response.

Influence of the distance between two voltage contacts on giant magneto-impedance of Co-based amorphous wires

The Co75Fe4.2Si8B12Nb0.8 amorphous wires of 30μm in diameter are produced by melt extraction and annealing at 450℃ for 20 min in vacuum with a longitudinal or transverse field of 40 kA/m. Distances between the two voltage contacts of 6, 5, 4 and 2 mm are obtained by moving the two voltage contacts towards the centre of the sample at the same time. Results indicate that magneto-impedance response is dependent on the distance significantly. As distance decreases from 6 to 2 mm, AZ/Z reduces from 609% to 95% and giant magneto-impedance （GMI） profiles change from two-peak to single-peak. Besides, field sensitivity improves from 0.47%/（A/m） to 0.76%/（A/m） when the single-peak GMI just appears. It is therefore concluded that actual measurements can be made comparable only by taking into account the influence of distance between two voltage contacts for a magneto-impedance measurement.

Effect of glass removal on the GMI effect of Co_(71.8)Fe_(4.9)Nb_(0.8)Si_(7.5)B_(15) amorphous glass-covered wires

During the past several years, giant magneto-impedance effect (GMI) in amorphous wires has generated growing interest in the science community because of their applications in sensors. The giant magneto-impedance effect in Co71.8Fe4.9Nb0.8Si7.5B15 amorphous glass-covered wires (AGCW) consists of strong changes in the high frequency impedance with a small DC magnetic field. When f=1 MHz, there is no GMI effect due to the fact that the magnetic penetration depth is higher than their radius. As the frequency increases, the GMI effect becomes important in both the glass-covered wire and the wire after glass removal. Field dependence of the impedance has a similar behaviour to the AGCW ones, when a tensile stress is applied to the wire without glass cover.

Giant Stress-Impedance Effect in Co_(71.8)Fe_( 4.9)Nb_(0.8)Si_(7.5)B_(15) Glass-Covered Amorphous Wires

The giant stress-impedance （GSI） effect in as-cast and DC current annealed Co71.8Fe4.9 Nb0.8Si7.5 B15 amorphous glass-covered wires is presented. The SI ratio of the as-cast sample exhibits negative GSI effect. For the sample annealed by 60 mA DC current, the SI ratio first increases with applied tensile stress, then decreases. The maximum ΔZ/Z ratio of 304% is obtained. Frequency dependence in the range from 1 to 110 MHz of the GSI effect is investigated. Experimental results show that the real part R and the imaginary part X of impedance play an important role at high frequency and low frequency, respectively. At 1 MHz, the maximum AX/X ratio of 1448% is obtained. At 110 MHz, the maximum AR/R ratio of 648% is obtained.

Magnetic Properties of Fe- and FeNi-based Amorphous Composite Ribbons

Ms-T curves and hysteresis loops were investigated for amorphous Fe78Si9B13, (FeNi)78(CrSiB)22, their lap-wound-cores, and their composite ribbons made by two-chamber-crucible technique. The properties of the lap-wound cores of the two kinds of ribbons are similar. For the composite ribbons, the intrinsic properties are the average of the two alloys. Their technological properties, i.e., hysteresis loops, however, are no longer the average of the two alloys. Instead, they show some dramatic changes compared to the lap-wound-cores. Especially, the shape of the hysteresis loop of the composite ribbon cores is largely different from that of lap-wound-cores. The reason for the difference is supposed to be internal stress induced from cooling after annealing.

Effect of Laser Annealing on Permeability Spectra in Co-based Amorphous Ribbon

We investigated the variation of permeability spectra and relaxation frequency in Co-based amorphous ribbon annealed by pulsed Nd:YAG laser at various annealing energy Ea. The complex permeability spectra varies sensitively with the annealing energy, where the spectra could be decomposed into two contributions from domain wall motion,μdw(f) and rotational magnetization μrot(f) by analyzing the measured spectra as a function of driving ac field amplitude. The magnitude of μdw(f) and μrot(f) in dc limit shows maximum at Ea = 176 mJ. The maximum relaxation frequency for rotational magnetization, determined by μ'(f) curve, is about 700 kHz at Ea=62 mJ but that for wall motion is about 26 kHz at 230 mJ. These variations reflect the increase of magnetic softness and microstructural change by the annealing.

Depth Profiles of Absorbed Hydrogen in Ni-Nb-Zr Amorphous Alloy Ribbons by Glow Discharge Optical Emission Spectroscopy

Depth profiles of absorbed hydrogen introduced by electrochemical charging and light elements were analyzed in Ni-Nb-Zr-H amorphous alloy ribbons using a glow discharge optical emission spectrometer. It was clarified that the absorbed hydrogen was comparatively well-distributed on the sample surface and that the content of the hydrogen decreased with increasing depth from the surface. That is, the amount of absorbed hydrogen on the surface was about 17 at %, while that inside the specimens decreased to several atomic percent. The depth profiles of the hydrogen which were close to the surface were slightly different between those on the roller side and those on the free side in the melt-spun ribbon. The difference is thought to originate from the existence of oxygen impurity on the surface and from the difference of the Zr content.

A NEW MAGNETIC EFFECT IN ZERO－MAGNETOSTRICTIVE AMORPHOUS WIRE

Ａ ＮＥＷ ＭＡＧＮＥＴＩＣ ＥＦＦＥＣＴ ＩＮ ＺＥＲＯ－ＭＡＧＮＥＴＯＳＴＲＩＣＴＩＶＥ ＡＭＯＲＰＨＯＵＳ ＷＩＲＥ￥ＢａｏＢｉｎｇｈａｏ（ＡｎｈｕｉｉｎｓｔｉｔｕｔｅｏｆＭｅｃｈａｎｉｃａｌａｎｄＥｌｅｃｔｒｏｎｉｃＥｎｇｉｎｅｅｒｉｎｇ，Ｗ...

Effect of Sn and Al additions on the microstructure and mechanical properties of amorphous Ti–Cu–Zr–Ni alloys

Amorphous Ti–Cu–Zr–Ni alloys with minor addition of Sn and Al were prepared by melt spinning technique.The effects of Sn and Al additions on the microstructures and mechanical properties of glassy ribbons were investigated.The amorphous state of ribbons was confirmed by x-ray diffraction and transmission electron microscopy,where those ribbons with Sn addition exhibited a fully amorphous state.The characteristic temperature indicates that Ti45Cu35Zr10Ni5Sn5 alloy has a stronger glass-forming ability,as proven by differential scanning calorimetry.Ti45Cu35Zr10Ni5Al5 alloy showed a better hardness of 9.23 GPa and elastic modulus of 127.15 GPa and good wear resistance.Ti45Cu35Zr10Ni5Sn5 alloy displayed a pop-in event related to discrete plasticity according to nanoindentation.When the temperature is below 560 K,Ti45Cu35Zr10Ni5Sn5 alloy mainly exhibits elasticity.When the temperature rises between 717 K and 743 K,it shows a significant increase in elasticity but decrease in viscoelasticity after the ribbon experiences the main relaxation at 717 K.When the temperature is above 743 K,the ribbon shows viscoplasticity.

电解水析氢反应的铁基非晶合金薄带催化剂研究进展

Pt基电催化剂是析氢反应的基准,然而低丰度和高成本制约了此类贵金属基催化剂的大规模应用,从而促使了替代材料的探索。铁基非晶合金具有无序原子排布结构,表现出独特的物理化学性质。受碱性溶液中的高效析氢反应启发,简述了铁基非晶合金薄带电催化剂的常见反应机理和设计策略,旨在为制备高性能电催化剂提供指导,包括杂原子掺杂、异质面构筑、应变及空位缺陷构建等。此外,原位表征技术和密度泛函理论在铁基非晶合金薄带电催化剂理论设计、反应过程、动态结构演变和机理揭示等方面发挥了重要作用。最后简要介绍了铁基电催化剂目前存在的挑战和未来的研究方向。

铁基非晶条带催化降解性能的退火晶化调控机理

非晶合金是原子结构长程无序的亚稳态材料,具有优异的催化降解性能,同时也很容易发生晶化,但晶化对催化降解性能的影响机理目前尚不明确.本文研究了退火晶化对Fe-Si-B-Cu-Nb工业非晶条带微观结构及其对酸性橙7催化降解性能的影响.研究发现:经460—580℃退火后,条带的催化降解性能大幅下降,其反应速率常数低于0.01 min–1,α-Fe析出相导致其非晶结构的破坏,降低了羟基自由基的形成速率;而经过650—700℃退火后,条带的催化降解性能显著提高,反应速率可提升至退火前的3.77倍,降解15 min时的脱色率达99.22%,为退火前的1.12倍,催化降解性能的提高得益于晶化相与金属化合物间的原电池效应及富集Cu团簇和零价铁之间的置换反应.本研究揭示了退火晶化对偶氮染料的铁基非晶条带催化降解性能的作用机理,为利用老化的铁基非晶工业条带处理印染废水、实现“以废治废”,提供了有益的理论与实验支撑.

Fe_(69.9)Cr_(22.6)Mo_(5.7)Cu_(0.6)Zr_(0.1)Nb_(0.8)W_(0.3)非晶合金在不同温度含氯溶液中的耐蚀性

为考察铁基非晶合金在不同温度的含氯溶液中的腐蚀性能,采用电弧熔炼结合真空甩带制备了Fe_(69.9)Cr_(22.6)Mo_(5.7)Cu_(0.6)Zr_(0.1)Nb_(0.8)W_(0.3)非晶条带,并通过动电位极化曲线、阻抗谱和浸泡实验研究了温度对合金在含氯溶液中耐蚀性的影响。结果表明:与316不锈钢相比,合金具有典型的非晶态结构,其耐蚀性显著增加。在25℃的3.5%(质量分数)NaCl溶液中,其自由面的耐蚀性与辊面相当,自腐蚀电流密度分别约为316不锈钢的18.9%、15.7%;在NaCl溶液中具有稳定的钝化特征,但钝化区间ΔE更宽。在45℃的NaCl溶液中,其自由面与辊面之间的耐蚀性差别显著增大,自腐蚀电流密度显著增加,ΔE变化不大。在80℃的37%盐酸中,其腐蚀速率相对于室温增加了2个数量级,但仍远低于316不锈钢2个数量级。温度的升高使非晶合金表面活性质点增加,氯离子的渗透能力增强,腐蚀反应速度加快。

高密度1728芯带状光缆的设计与制造

目前现有的地下管道已经非常拥挤,可以安装在管道中的光缆数量极为有限,为网络扩容带来很大的困难。本文介绍了一种1728芯的高密度、小直径带状光缆,可以有效的解决在现有的管道资源下,进一步提高传输能力的难题。

Microstructures of Ti–Ni–Fe wire after severe cold-drawing and annealing

The microstructures and mechanical properties of Ti–47 at%Ni–3 at%Fe shape memory alloy wire under the condition of severe cold-drawing at room temperature and different postdeformation annealing processes were intensively investigated using transmission electron microscope(TEM),X-ray diffraction(XRD),Vickers microhardness tester and electron tensile tester.It is indicated that the structure of the alloy evolves into a predominant amorphous structure with a trace of nanocrystalline B2 phase after the cold-drawing of 76%areal reduction.Postdeformation annealing process exerted significant influence on the microstructure and mechanical properties.Crystallization occurs when the cold-drawn wire was annealed at 300℃ for 30 min.The ultimate tensile strength and ductility as well as the superelasticity of the wire are improved significantly by cold-drawing plus postdeformation annealing.