Amorphous Alloy Ribbons Research Articles

Formation, thermal stability and soft magnetic properties of Fe-Co-B-Si amorphous alloys with ultrahigh saturation magnetic induction of 2.0 T

This paper studies the influence of metallic element composition on the formation ability, thermal stability and magnetic properties of melt-spun (Fe1-xCox)B15–19Si1 (x =0.2–0.4) amorphous alloy ribbons. The maximum metal concentration at which an amorphous phase is formed during melt spinning has been determined in conjunction with the metal content dependence of crystallization processes and crystallized phases. The amorphous (Fe0.8Co0.2)84B15Si1 alloy with the highest metal content in an optimally annealed state exhibits an extremely high saturation induction (MS) of 2.0 T, low coercive force of 7.6 A m−1, high effective permeability of 13500 at 1 kHz and low core losses of 5.5 W kg−1 at 100 mT and 19.7 W kg−1 at 200 mT at 10 kHz which have not been simultaneously obtained for all kinds of soft magnetic materials up to date. The replacement of Fe with Co significantly increases the Curie temperature of the amorphous phase, resulting in very high thermal stability of the high MS alloys. The combination of excellent soft magnetic properties with ultrahigh MS value makes them candidates for use in highly loaded high-speed electric motors capable of operating at temperatures up to 473 K.

Experimental investigation of comprehensive performance by tailoring the proportion of late transition metals in quinary Fe-Co-Ni-Si-B amorphous alloys

We fabricated the Fe-Co-Ni-Si-B multi-principal element alloys by vacuum melt-spinning method. The effects of late transition metals proportion in quinary alloy ribbons on the formation, phase structure, thermal stability, microhardness, corrosion resistance and soft magnetic properties were investigated. The melt-spun structure consists of an amorphous single phase for all the specimens. The surfaces of glassy ribbons are rather flat and flawless and the average surface roughness is 0.351 nm or below. The initial crystallization temperature (Tx) and supercooled liquid region (ΔTx) of alloy system decrease by degrees with increasing Co and Ni content, showing the maximum values of 753.0 K and 60.0 K for Fe60Co10Ni10Si6B14 alloy. But the glass transition temperature (Tg) seems to barely change and maintain approximately 692.0 K. All the as-received alloy ribbons exhibit good bending ductility and acceptable Vickers microhardness ranging from 671 to 785 HV0.5. The amorphous alloy ribbons present a gradually wide passive potential range (ΔE) with the decrease of Fe content, but the corrosion current density (Icorr) becomes larger. The smallest Icorr value is 1.785 μA·cm-2 for Fe60Co10Ni10Si6B14 alloy and the widest ΔE value is about 0.272 V for Fe26Co27Ni27Si6B14 alloy. The saturation magnetization of these glassy alloys reduces from 165.0 to 112.0 emu/g as the Fe content decreases. Meanwhile, the coercivity also changes from 14.25 to 6.70 A/m. This paper offers a brand-new perspective to understand the role of late transition metals on the various physicochemical properties of quinary Fe-Co-Ni-Si-B amorphous alloys.

Flexible Mini‐Inductors with Ultra‐High Inductance Density Directly Cut from Soft Magnetic Amorphous Alloys by Femtosecond Laser

AbstractInductors are indispensable parts in power modules of electronic devices. With the rapid development of flexible and wearable electronic devices, developing flexible micro‐inductors with large energy storage has become an urgent task. In this research, a sophisticated femtosecond laser ablation technique is employed to craft circular spiral mini‐inductors via selective etching of soft magnetic amorphous alloy ribbons. Remarkably, while these inductors possess dimensions akin to human fingerprints, they demonstrate an impressively elevated inductance value of ≈1.15 µH at 1 MHz. The inductance density is ≈280–390 nH mm−2, which is ≈10 times larger than conventional circular spiral inductors and is attributed to the high permeability of the amorphous alloys. Furthermore, the inductors showcase commendable flexibility, marked by stellar elasticity and a bending endurance exceeding 2500 cycles, thanks to the amorphous alloys' superior elastic strain limit. When integrated with an LM2576‐3.3BT buck converter, the fabricated inductor achieved a peak power conversion efficiency nearing 70%. These findings underscore the potential of such flexible mini‐inductors in the landscape of flexible electronics.

Peculiarities of Magnetization Processes of Cobalt-Based Amorphous Alloy Ribbons in the As-Quenched State

Peculiarities of Magnetization Processes of Cobalt-Based Amorphous Alloy Ribbons in the As-Quenched State

Non-Isothermal Analysis of the Crystallization Kinetics of Amorphous Mg72Zn27Pt1 and Mg72Zn27Ag1 Alloys.

In this study, thin ribbons of amorphous Mg72Zn27Pt1 and Mg72Zn27Ag1 alloys with potential use in biomedicine were analyzed in terms of the crystallization mechanism. Non-isothermal annealing in differential scanning calorimetry (DSC) with five heating rates and X-ray diffraction (XRD) during heating were performed. Characteristic temperatures were determined, and the relative crystalline volume fraction was estimated. The activation energies were calculated using the Kissinger method and the Avrami exponent using the Jeziorny-Avrami model. The addition of platinum and silver shifts the onset of crystallization towards higher temperatures, but Pt has a greater impact. In each case, Eg > Ex > Ep (activation energy of the glass transition, the onset of crystallization, and the peak, respectively), which indicates a greater energy barrier during glass transition than crystallization. The highest activation energy was observed for Mg72Zn27Pt1 due to the difference in the size of the atoms of all alloy components. The crystallization in Mg72Zn27Ag1 occurs faster than in Mg72Zn27Pt1, and the alloy with Pt has higher (temporary) thermal stability. The Avrami exponent (n) values oscillate in the range of 1.7-2.6, which can be interpreted as one- and two-dimensional crystal growth with a constant/decreasing nucleation rate during the process. Moreover, the lower the heating rate, the higher the nucleation rate. The values of n for Mg72Zn27Pt1 indicate a greater number of nuclei and grains than for Mg72Zn27Ag1. The XRD tests indicate the presence of α-Mg and Mg12Zn13 for both Mg72Zn27Pt1 and Mg72Zn27Ag1, but the contribution of the Mg12Zn13 phase is greater for Mg72Zn27Ag1.

Heterogeneous high-entropy catalyst nanoparticles for oxygen evolution reaction: Impact of oxygen and fluorine introduction

High-entropy catalysts attract rising attention for promoting oxygen evolution reaction (OER) due to the advantages of multiple catalytic active sites, unique lattice distortion effect, interatomic d-band ligand effect, etc. However, it still needs to design new high-entropy catalysts with low cost and high efficiency to meet the requirement of large-scale applications. In this study, AlNiCuCoFeY amorphous alloy ribbon is prepared by melt spinning method. Then, the ribbon is etched in HF solution to form a nanoparticle modified ribbon, whose superficial species are further conversed to high-entropy oxides/Al alloy (HEO/Al alloy) or high-entropy fluorides/Al alloy (HEF/Al alloy) heterogeneous nanoparticles with a diameter of ∼20 nm by subsequent oxidization or fluorination process. Herein, the oxidized metallic elements with high valence state can promote the adsorption of OER. Due to the large surface area, multiple active sites, and the synergistic effect of different species, the HEO/Al alloy or HEF/Al alloy composite only need 293 and 261 mV overpotential to afford 10 mA cm−2 current density. This work discusses the design of high-entropy electrocatalysts and demonstrated a promising route to improve their OER electrocatalytic performance.

2D X-ray diffraction method for evaluating the local crystallization of Fe-based amorphous alloy ribbon induced by ultrashort pulsed laser local heating

Fe-based amorphous alloys, which exhibit excellent soft magnetic properties, are difficult to machine, owing to their high strength, toughness, and hardness resulting from their unique structures. The authors proposed a novel blanking method that improves the machinability by crystallizing only the local regions involved in machining, thereby reducing the local strength and toughness. Because the micro-region mechanical properties of amorphous alloys vary greatly depending on the precipitated crystal species and volume fraction, it is necessary to nondestructively investigate the type of microstructure achieved by local heat treatment to determine the appropriate blanking conditions. However, an appropriate method for investigating crystals precipitated locally in an amorphous matrix is yet to be established. In this study, we used the 2D X-ray diffraction method to investigate the local crystallization of an Fe-based amorphous alloy ribbon after local heat treatment using an ultrashort pulsed laser. Furthermore, the 2D method was used to investigate the residual stresses in the fully crystallized amorphous alloy ribbons, and the results were compared using the sin2(ψ) method. The 2D method detected the slightly precipitated crystals in a local area with a radius of about 40 µm in the amorphous matrix. The integrated intensity of the diffraction peaks can be used to predict the internal structure after local heat treatment. Furthermore, the 2D method could measure residual stress with smaller error than the sin2(ψ) method. The core-shell crystals precipitated by heat treatment exhibited a compressive residual stress of −82 MPa to −67 MPa in the core Fe3B crystals and tensile residual stress of 39–60 MPa in the shell α-Fe crystals, approximately. The residual stress values of the precipitated crystals depended on the direction of rotation of the quenching roll used in the production of the amorphous alloy ribbons.

Nonuniformity of Magnetization Processes of a Co-Based Amorphous Alloy Ribbon in the As-Quenched State

Nonuniformity of Magnetization Processes of a Co-Based Amorphous Alloy Ribbon in the As-Quenched State

Study of Crystallization Kinetics of (Fe50Ni50)73.5Si13.5B9Nb3Cu1 Ribbons Prepared by Rapid Cooling Technique

Amorphous alloy ribbons of (Fe50Ni50)73.5Si13.5B9Nb3Cu1 were fabricated by rapid cooling technique on single copper wheel. After fabrication, the crystalline structure of the ribbons were examined by X-ray diffraction method. The results show that the samples possess a complete amorphous state. The crystallization process was studied by using a differential thermal analyzer (DSC). The DSC analysis show that there are two exothermic peaks corresponding to two crystalline phases appeared in the alloy ribbons. By changing the heating rate (i.e. 5, 10, 15, 20 and 25 oC/min) and by using the Kissinger method, The activation energy of crystallization of the crystalline phases determined for one phase was found to be E1 = 350 kJ/mol and for other one, E2 = 375 kJ/mol. Based on these results, we have chosen the appropriate annealing mode for the alloy ribbons. After annealing, the alloy ribbons were achieved nanocrystalline states of FeNi and α-Fe nano-particles with the grain size ranging from 5 to 15 nm and the fraction of crystallization between the crystalline and amorphous phases of 46, 67, 85 and 96 % respectively for the annealing regimes at 500 oC for 20, 30, 50 and 60 minutes.

Magnetostriction of Fe-rich FeSiB(P)NbCu amorphous and nanocrystalline soft-magnetic alloys

The compositional effect of magneto-elastic and magnetostriction properties of Fe-rich Fe81B15−xPxSi2Nb1Cu1 (ii) Fe82B14−xPxSi2Nb1Cu1 and (iii) Fe83B13−xPxSi2Nb1Cu1 (x = 0, 4, 8) amorphous and annealed nanocrystalline alloy ribbons were investigated. The present study adds knowledge to the limited magnetostriction literature available for Fe-rich nanocrystalline alloys by systematically varying the Fe and P content. A combination of Becker-Kersten and small angle magnetization rotation (SAMR) techniques has been employed for the magnetostriction (λs) evaluation. Both the as-quenched and nanocrystalline ribbons exhibit large positive magnetostriction and show strong compositional dependence to the P content. In the as-quenched condition, 4 at% P addition shows maximum magneto-elastic response and magnetostriction constant, with Fe81B11P4Si2Nb1Cu1 alloy exhibiting a maximum of + 52 ppm and P-free Fe83B13Si2Nb1Cu1 alloy exhibiting a minimum of + 27 ppm. In the nanocrystalline state, a slight reduction of magnetostriction is seen for all alloys, with a maximum of + 32 ppm (4 at% P) and a minimum of + 22 ppm (P-free) in Fe83 at% alloys. The unusual large magnetostriction of optimally annealed samples is attributed to the relatively low crystal volume fraction (30–45%) of nanocrystalline ribbons. The lowest magnetostriction of Fe83B13Si2Nb1Cu1 alloy in both as-quenched and annealed state is explained based on ribbon structural heterogeneity consisting of crystal nuclei and textured α-Fe surface crystallization. The study reveals a contradictory response of magneto-crystal anisotropy (grain size reduction) and magneto-elastic anisotropy to the P addition and ribbon structural heterogeneity. The study discusses the implications of the large magneto-elastic anisotropy associated with Fe-rich nanocrystalline ribbons and the way forward for improving their magnetic softness.

Shear Transformation Zone and Its Correlation with Fracture Characteristics for Fe-Based Amorphous Ribbons in Different Structural States

Fe-based amorphous alloys often exhibit severe brittleness induced by annealing treatment, which increases the difficulties in handling and application in the industry. In this work, the shear transformation zone and its correlation with fracture characteristics for FeSiB amorphous alloy ribbons in different structural states were investigated. The results show that the bending strain decreases sharply with the annealing temperature increase, accompanied by decreased shear band density and the induced plastic deformation zone. Furthermore, the microscopic fracture surface features transform from a micron-scale dimple pattern to nano-scale dimples and periodic corrugations. According to nano-indentation results, the strain rate sensitivity and shear transformation zone volume change significantly upon annealing treatment, which is responsible for the deterioration of bending ductility and the transition of microscopic fracture surface features.

Magnetic shielding for large photoelectron multipliers for the OSIRIS facility of the JUNO detector

We present technical design and characteristics of the magnetic shield developed for 20" PMTs of the low-background OSIRIS facility. A ribbon of amorphous alloy with extreme magnetic permeability was used in its design, providing excellent efficiency in screening the Earth's magnetic field with a relatively small amount of material. The mass of materials is crucial to construction of low-background facilities because of radioactive backgrounds. Using amorphous materials is cost-efficient compared to other methods for screening the Earth's magnetic field.

(Fe-Ni)-based glassy alloy containing Nb and Cu with excellent soft magnetic properties

Magnetic properties of amorphous Fe38Ni38B12P5Si3Nb3Cu1 alloy ribbons have been investigated in as-spun and annealed states with the aim of developing an ultrasoft magnetic material which is expected to be used in advanced information data devices. A small amount of simultaneous addition of Cu and Nb to a FeNi-metalloid amorphous alloy system caused the change in crystallization process from eutectic type to the primary one. After annealing at the temperature just below the glass transition temperature (Tg), the glassy alloy ribbon exhibit excellent soft magnetic properties, very low coercive force of 1 A/m and extremely high effective permeability of 7.5·104 at 1 kHz which have not been obtained for any kinds of Fe- and Ni-based amorphous alloys, in spite of relatively low saturation magnetic flux density of 0.86 T. The further increase in annealing temperature causes the precipitation of nanoscale fcc particles with a size of about 7 nm including a high density of planar faults and the resulting nanostructure alloy also exhibits good soft magnetic properties with low Hc below 2 A/m. The formation of nanostructure fcc-(Fe,Ni) + glass soft magnetic alloys is also novel. The syntheses of the new Fe-Ni-based glassy and nanocrystalline [fcc(Fe,Ni) + glass] alloy ribbons with ultrasoft magnetic properties are encouraging as a new type of energy saving-type soft magnetic material.

Flexible amorphous (Fe0.5Co0.5)70B21Ta4Ti5 high-entropy alloy catalyst showing high activity and stability in degrading Eosin Y

The (Fe0.5Co0.5)70B21Ta4Ti5 amorphous high-entropy alloy (HEA) ribbon without surface pretreatment shows the excellent photocatalytic efficiency and recycling stability in the degradation of Eosin Y. Even after 20 cycles, the amorphous HEA ribbon is still mainly in the amorphous state and remains flexible. Its degradation effect is compared with Fe-Si-B amorphous ribbon, Fe0 powder and TiO2 powder, showing superior catalytic performance.The alternating evolution of Ti(Ta)-rich passive film and Fe(Co)-rich fresh layer effectively promotes and appropriately inhibits the reaction to ensure the high efficiency and continuity of catalysis. The underlying mechanisms of salient photocatalytic activity are proposed by the introductions of nano-twins and stacking faults, multiple superimposed heterogeneous interfaces, and mutual conversion of Fe/Co with various valence.

Degradation of azo dye by Sono-Fenton method based on Fe-based amorphous alloy ribbons

Azo compounds are difficult to remove from wastewater by conventional wastewater treatment methods. In this study, an Fe-based amorphous alloy was used as a catalyst for the degradation of azo dyes by Sono-Fenton method. The effects of pH, oxidant dosage and temperature on the reaction process of Sono-Fenton and its mechanism of action were investigated. The fastest degradation rate was observed at pH=2, an experimental temperature of 35°C and a H2O2 dosage of 100 μL, with a degradation time of 25 min.

Corroded Fe78Si9B13 amorphous alloy as electrocatalyst for oxygen evolution reaction of water splitting

In this work, different amounts of FeOOH are in situ generated on an amorphous Fe78Si9B13 alloy ribbon by potentiostatic cathodic corrosion treatments for different time, including 0.5 h, 1 h, 2 h and 5 h, which are marked as the R-0.5h, R-1h, R-2h and R-5h, respectively. Afterwards, the corroded samples are investigated as electrocatalysts for the oxygen evolution reaction (OER) of water splitting in 1 M KOH. An appropriate amount of FeOOH not only provides more active sites, but also generates hydroxy1 radicals (OH˙) to greatly improve the efficiency of electronic transmission. However, when the surface of samples is covered by the thick and dense FeOOH layer, the catalytic reaction rate sharply decreases. The R-1h sample shows the best OER catalytic performances, which can achieve an overpotential of 356 mV at a current density of 10 mA cm−2 and the Tafel slope of 45 mV dec−1.

Enhanced degradation performance of Fe75B12.5Si12.5 amorphous alloys on azo dye.

The Fe75B12.5Si12.5 and Fe75B12.5C12.5 amorphous alloy ribbons were prepared by the melt spinning method. The decolorization performances of these ribbons were investigated in details. It is found that the Fe75B12.5C12.5 amorphous ribbons and Fe75B12.5Si12.5 annealed ribbons only adsorbed the azo dye molecules, with no chemical degradation process. However, the Fe75B12.5Si12.5 amorphous ribbons can reduce -N = N- to -NH2 because of their high reactivity and the local galvanic effect that occurred during the reaction to accelerate electron transfer. The reaction rate constant kobs is 0.0872min-1, 0.0474min-1, and 0.0064min-1 for Fe75B12.5Si12.5 amorphous ribbons, Fe75B12.5C12.5 amorphous ribbons, and Fe75B12.5Si12.5 annealed ribbons in the same condition, respectively. Fe75B12.5Si12.5 amorphous ribbons can effectively degrade Acid Orange II (AO II) azo dyes and achieve decolorization by breaking azo bonds in the dye in a short time, indicating the prominent capacity of Fe75B12.5Si12.5 ribbons on the degradation of AO II. Furthermore, the influence of chemical factors such as ribbons thickness, reaction temperature, initial pH, and AO II concentration of the solution on the reaction rate constant kobs of Fe75B12.5Si12.5 amorphous ribbons had also been studied. The kobs can reach 0.177min-1 under optimal conditions. In addition, all the degradation processes in this work were fitted well with the pseudo-first-order kinetic model. The results are guidance for the practical applications, and they have important implications in developing Fe-based amorphous alloys for functional application materials in the field of wastewater treatment.

Electrochemical hydrogen storage, mechanical and thermal behaviors of novel Mg-based alloy

In this study, Mg65Ni25Y5B5 metallic glass synthesized by using the melt-spinning technique was examined in terms of its electrochemical hydrogen-storage characteristics and mechanical and thermal behaviors. The X-ray diffraction and scanning electron microscopy results indicated that the alloy ribbon has a fully amorphous structure. The thermal behavior of the alloy ribbon was determined using flash differential scanning calorimetry (DSC). According to flash DSC results, the amorphous alloy ribbon exhibited a distinct glass transition temperature (T g) and a wide supercooled liquid region (ΔT x = T x − T g) before crystallization. Accordingly, T g and ΔT x are 195 and 63°C, respectively. The mechanical behavior of the magnesium (Mg)-based alloy at room temperature was determined by means of a Vickers microhardness (HV) tester. The microhardness value of the alloy ribbon was measured as 336.8 HV. The discharge capacity of the Mg65Ni25Y5B5 alloy reached 313 mAh/g. The cycle stability revealed that the alloy ribbon protected at least 76.7% of its initial discharge capacity at the 12th charge–discharge cycle.

Annealing and electrochemically activated amorphous ribbons: Surface nanocrystallization and oxidation effects enhanced for oxygen evolution performance

Annealing and cyclic voltammetry (CV) are essential for the activation of amorphous alloy ribbons. Various amorphous alloy ribbons have been activated in the fields of environmental catalysts using either annealing or CV. However, the combination of the two methods for improving the oxygen evolution reaction (OER) performance has rarely been reported. This combination is expected to significantly improve the OER performance of amorphous ribbons. Here, we developed an “annealing +CV-activation” integrated strategy to treat a free-standing NiFeBSiP ribbon, which as an efficient and stable oxygen-evolving electrode. The “annealing +CV-activation” strategy induces the nanocrystallization and oxidation effects on the surface of the NiFeBSiP ribbon. The effects significantly increase the electron transfer ability, the Ni/Fe/P oxidation state and the surface area of the NiFeBSiP ribbon, which consequently leads to enhancing the OER performance. As a result, the treated ribbon exhibits a low overpotential of 269 mV at 10 mA cm−2 and a small Tafel slope of 40.5 mV dec−1, which are much better than the OER performance of the as-spun ribbon. The enhanced OER performance of the NiFeBSiP ribbon demonstrates the significant and promising effect of the “annealing +CV-activation” integrated strategy for designing high-efficiency amorphous alloy ribbons electrocatalysts.

Electric explosion of amorphous iron alloy ribbons in water and in ethylene glycol

Electric explosions of amorphous ribbons (Fe45Co45Zr7B3 HITPERM, Fe73.5Si15.5B7Nb3Cu1 FINEMET, and bulk amorphous Fe71.6Mn0.6Si3.4C12.3B12.2) were studied in water and for the bulk amorphous alloy in ethylene glycol, in order to study whether the amorphous state can be preserved in the process. Formed products were collected and analyzed by Scanning Electron Microscopy, X-ray diffraction, Mössbauer spectroscopy, and High-Resolution Transmission Electron Microscopy. Chemical reactions have taken place in large extent between melted and evaporated components of ribbons and the decomposed cooling media. The oxidation reactions removed quickly the glass-forming elements (Zr, B, Si) from the metallic particles. Oxides were formed both on surface of globules and in separate phases from evaporated components. The amorphous state was partly retained in FINEMET, and to a greater extent in bulk amorphous alloy. Chemical interactions were more limited in ethylene glycol and carbon atoms formed from the decomposed coolant contributed to stabilization of amorphous phase.Graphical abstract