Fe-based Amorphous Ribbons Research Articles

Energy loss analyses of amorphous magnetic ribbons by multi-frequency single sheet tester

Due to low values of both thickness and conductivity, Fe-based amorphous soft magnetic ribbon (AR) is an attractive alternative to crystalline silicon steel (CS) for elevated frequencies f up to several kHz. On the other hand, for corresponding tests of losses P, the only standardized method is restricted to just 400 Hz. Recently, we reported “Physically Consistent Loss Testing” (CLT) for loss tests of CS for f up to 10 kHz. Here, we describe an adaptation of a corresponding multi-frequency single sheet tester for AR-applications. The CS single sheet is replaced by six 50 cm long and 17 cm wide ARs, loosely inserted into a paper envelope. This “envelope technique” provides (i) simple sample arrangement in an absolutely flat state, (ii) high repeatability, (iii) robust sensor signals, (iv) avoidance of loss increases due to magneto-mechanical effects, and (v) averaging over thickness variations of ARs through as much as 100 g of sample mass. Here, we report the results of frequency analyses for sinusoidal magnetization in the longitudinal direction for induction up to 1.5 T for f < 1 kHz and 0.4 T for 10 kHz, with P up to 50 W/kg. Anisotropy tests confirm a very weak dominance of the transverse direction. In conclusion, CLT proves to be an effective tool for loss tests on both CS and AR as a physically consistent principle. Therefore, for the ongoing standardization of SST with H-coil, we recommend considering the integration of the “envelope technique” in order to establish rapid and universal multi-frequency loss testing.

Annealing crystallization control mechanism of catalytic degradation properties of Fe-based amorphous ribbons

Amorphous alloys are meta-stable materials with long-range disordered atomic structure, which have excellent catalytic degradation performance and are also susceptible to crystallization, but the mechanism of the effect of crystallization on their catalytic properties has not been clarified. Therefore, the effect of the annealing crystallization process on the microstructure of Fe-Si-B-Cu-Nb industrial amorphous ribbons and their catalytic degradation properties for acid orange 7 are investigated in this work. It is found that the catalytic degradation performance of the ribbons decreases dramatically after having been annealed at 460–580 ℃ , and its reaction rate constant is less than 0.01 min<sup>–1</sup>. The main reason is the formation of <i>α</i>-Fe precipitation phase in the ribbons after having been annealed at high temperatures and the destruction of the substable amorphous structure. These reduce the rate of hydroxyl radical formation. In contrast, the catalytic degradation performance of the 650–700 ℃ annealed ribbons increases significantly, which increases to 3.77 times the degradation rate of the as-cast ribbons. The decolorization rate of acid orange 7 by the annealed ribbons reaches 99.22% within 15 min, which is 1.12 times that of the as-cast ribbons. The improvement of the catalytic degradation performance is attributed to the primary cell effect between the crystalline phase and the metal compounds and the substitution reaction between the Cu-enriched clusters and zero-valent iron. In this study, the influence mechanism of annealing crystallization on the performance of Fe-Si-B-Cu-Nb industrial amorphous ribbons for degrading azo dyes is revealed, which provides theoretical and experimental support for using aged iron-based amorphous ribbons to purify printing and dyeing waste-water and achieve “purification of waste-water by using alloy waste”.

Structural responses of heterogeneous FeB(P)CCu amorphous alloys under nanoindentation

The nano-scaled structural heterogeneity is closely associated with the magnetic softness and mechanical properties of Fe-based amorphous alloys. However, limited by the shape and size of ribbons, the details of the atomic-scale structural evolution in ribbons under external stimulation are still missing. In this work, Maxwell-Voigt model with 2 K units and 1 Mx unit was employed to investigate the structural response of FeBCCu amorphous ribbons by substitution of P for B during creeping process under nanoindentation. The P-added alloy exhibited a more sensitive mechanical response at various loading rates, especially for the reduction of hardness and the increase of maximum indentation depth and creep displacement. With the help of creep analysis using above Maxwell-Voigt model, both types of defects were inclined to be activated at a quasi-static loading mode in P-added alloy, and the small size defects seemed to be easily activated and finally coupled into large defects in the fast loading mode, revealing the atomic diffusion and reconstruction process of activated defects. These types of defects evolved into the response of structural heterogeneity to external stimulation, manifesting a large deformation behavior during creeping. This work enlightens the comprehensive insights into the evolution of structural defects in Fe-based amorphous ribbons and has certain guiding significance for the structural design of high-performance alloys.

Laser punching of soft magnetic Fe-based amorphous ribbons

Soft-magnetic Fe-based amorphous materials are indispensable in electronic components. However, traditional processing methods (mechanical punching or wire cutting) degrade the amorphous structure, introduce stress, and are inefficient. To overcome these limitations, we introduce a precision processing technique for the Fe-based amorphous ribbons, namely laser punching. We compare two laser types: the picosecond pulse ultraviolet (PS-UV) laser, representing “cold” lasers, and the continuous-wave infrared (CW-IR) laser, epitomizing “hot” lasers. Our results demonstrate that the PS-UV laser can produce intricate geometries with minimal thermal or stress-induced effects. In contrast, the CW-IR laser induces nano-crystallization and crinkling due to heavy thermal effect. As an example, we successfully craft an amorphous motor stator using the PS-UV laser-processed ribbons, which exhibits considerably reduced iron losses compared to that fabricated with CW-IR laser. The reduction in iron loss and enhanced efficiency underscores the potential of PS-UV laser punching as a promising method for manufacturing amorphous motors.

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.

Enhanced Giant Magnetoimpedance Properties of Fe-Based Amorphous Ribbons by Coating Soft Magnetic Film

Enhanced Giant Magnetoimpedance Properties of Fe-Based Amorphous Ribbons by Coating Soft Magnetic Film

Influence of iron content in Fe-based amorphous alloy catalysts on degradation of azo dyes by fenton-like process

Degradation of organic pollutants in industrial wastewater has become one of the biggest problems that are threatening the environment, and correspondingly it is a priority for scientists to find a solution. In this work, we study the effect of the iron content in Fe-based amorphous ribbon catalysts (Fe78+xSi9B13-x, x = 0, 1 and 2) in degradation of Direct Blue 6 (DB 6) azo dye by Fenton-like process. We evaluated the catalytic efficiency by changing experimental conditions with the aim to optimize the degradation performance. The amorphous Fe80Si9B11 ribbon showed the highest catalytic activity with its ability to degrade DB 6 by 94.65% within 15 min Fe80Si9B11 ribbon provides more reactive sites than what generates the most hydroxyl radicals (. OH) and thus increases the degradation reaction. Degradation efficiency can be improved by increasing the reaction temperature and ribbons dosage, a correct amount of H2O2 but decreases with increasing initial pH value and concentration of DB 6. Fe80Si9B11 amorphous ribbons can be reused up to 12 times in optimal conditions, which confirms a good reusability. The excellent performance in catalytic activity and reusability of Fe-based amorphous alloy catalysts will contribute to wastewater treatment.

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.

Fabrication of Flexible Supercapacitor Electrode Materials by Chemical Oxidation of Iron-Based Amorphous Ribbons.

A flexible electrode constructed from Fe-based amorphous ribbons decorated with nanostructured iron oxides, representing the novelty of this research, was successfully achieved in one-step via a chemical oxidation method, using a low concentration of NaOH solution. The growth of metal oxides on a conductive substrate, which forms some metal/oxide structure, has been demonstrated to be an efficient method for increasing the charge transfer efficiency. Through the control and variation of synthetic parameters, different structures and morphologies of iron oxide were obtained, including hexagonal structures with a hollow ball shape and rhombohedral structures with rhombus-like shapes. Structural and morphological characterization methods such as X-ray diffraction and SEM morphology were used on the as-synthesized composite materials. The supercapacitor properties of the as-developed amorphous ribbons decorated with Fe2O3 nanoparticles were investigated by cyclic voltammetry, galvanostatic charge discharge, and electrochemical impedance spectroscopy. The flexible supercapacitor negative electrode demonstrates a specific capacitance of 5.96 F g-1 for the 0.2 M NaOH treated sample and 8.94 Fg-1 for the 0.4 M NaOH treated sample. The 0.2 M treated negative electrodes deliver 0.48 Wh/kg at a power density of 20.11 W/kg, and the 0.4 M treated electrode delivers 0.61 Wh/kg at a power density of 20.85 W/kg. The above results show that these flexible electrodes are adequate for integration in supercapacitor devices, for example, as negative electrodes.

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.

Experimental Study on 3D Printing of Fe-based Amorphous Ribbon Based on Electric Pulse

Experimental Study on 3D Printing of Fe-based Amorphous Ribbon Based on Electric Pulse

Core loss reduction through a laser scribe on Fe-based amorphous ribbon surface for transformer cores

Core loss reduction of an Fe-based amorphous ribbon for distribution transformer cores by laser scribe is researched and the efficacy of core loss reduction by laser scribe is compared with that by fish scale-formation during ribbon casting. Core loss reduction by laser scribe is found to be more effective than fish scale and the reduction is prominent in a 53 kg single phase core tested. Core loss reduction is realized through the reduction of anomalous eddy current loss by domain refinement. Although a fish scale ribbon shows refined magnetic domains in static magnetic domain observation, effective magnetic domains are not refined and the reduction of anomalous eddy current loss by fish scale is small. Core building factor, the ratio of core loss of a transformer core to that of a strip ribbon, is found to be increased due to higher anomalous eddy current loss in a 53 kg single phase core tested. Building factor is reduced from about 2 to 1.5 by reducing anomalous eddy current loss by laser scribe.

Structures, interfaces and thermodynamic stability of nanocrystalline phases in rapidly solidified Fe-based amorphous nanocomposite ribbon, powder and coating

Fe-based amorphous nanocomposite with nominal composition Fe 58.82 Cr 11.12 Mo 1.52 Si 4.16 B 15.12 P 8.88 C 0.39 (at%) has been processed through melt-spinning, melt-spinning followed by ball milling and thermal spray deposition of coating onto a mild steel substrate. X-ray diffraction and electron microscopy characterization of the processed alloy reveals that the melt-spun ribbon is mostly amorphous with uniform distribution of very fine crystals of α-Fe and oP30 (Fe 2 B 7 ) phase. In the melt-spun followed by ball milled powder mainly cI58 (Fe 18 Cr 6 Mo 5 ), tP30 (Fe 62 Cr 34 Mo 4 ) and mI32 (Fe 5 C 2 ) phases are obtained. However, the tP30 (Fe 62 Cr 34 Mo 4 ) phase while ball milling undergoes distortive changes locally to produce oC68, tP60 and tP58 phases with similar composition. The interface between the two structures is considerably strained. In the coating, cF118 (Fe 18 Cr 6 Mo 5 ) and oI92 (Fe 62 Cr 34 Mo 4 ) are observed in the amorphous matrix. Essentially the cF118 and oI92 can be seen as a structural derivative of cI58 and tP30 phases respectively. Local composition fluctuation and availability of a suitable nucleation condition leads to the nucleation of crystalline phases in the amorphous matrix in the melt-spun ribbon. In the melt-spun followed by ball milled powder further distortive changes are observed locally, which leads to the formation of polymorphically related phases to tP30 phase. Even though all the phases are crystallographically quite complicated, they are all derived from either the tP30 (Fe 62 Cr 34 Mo 4 ) phase or cI58 (Fe 18 Cr 6 Mo 5 ) phases. Thermodynamic calculations through Miedema’s model indicates that the nominal composition of the alloy lies at the boundary of glass forming composition. The crystal compositions, although different from the nominal composition of the alloy, lies in the crystal forming composition range. Local composition fluctuation, favorable thermodynamic conditions for nucleation and growth leads to the crystal nucleation. Although all the phases are crystallographically different, they have similar polyhedral order in them. The polyhedral structures cannot be correlated with Frank-Kasper or Bernal deltahedral phases. This is a significant difference between metal-metalloid glasses with its metal-metal counterpart. • Hagg phases and Fe-Cr-Mo intermetalic phases evolve in a Fe-based BMG forming alloy after processing through different solidification routes. • Different polymorphs of Fe-Cr-Mo intermetallics evolve after processing through different solidification routes. • Contrary to the metal-metal glasses, polyhedral structures of the intermetallics do not directly corroborate with Frank-Kasper polyhedra or Bernal deltahedra. • Formation of structurally different polymorphs in the same alloy indicates that the energy difference between two polymorphs is very little. • Miedema calculations show that the alloy composition lies in the boundary region of the glass forming composition range and composition fluctuation is responsible for nucleation of nanocrystalline phases.

Laser patterning assisted devitrification and domain engineering of amorphous and nanocrystalline alloys

We have investigated laser-patterning and devitrification as a novel method to realize emergent properties in modified regions at the ribbon surface consisting of periodic localized laser spots thermally treated under rapid heating and cooling conditions. Fe-based amorphous ribbons were annealed for systematically varied laser power. Extremely high heating and cooling rates on the order of 108-1010K/s have been estimated by finite element analysis simulations. Observations suggest surface melting followed by rapid solidification fast enough to quench and form an amorphous structure upon cooling. Diffusion of heat occurs from the laser irradiated surface region so that a finite volume of material surrounding this region rises in temperature above the crystallization temperature relevant for conventional isothermal annealing experiments. The underlying mechanism of laser annealing and consequences of heat transients involved are discussed in terms of impacts upon micro/nanostructure, residual stresses, and magnetic domain structure surrounding the laser irradiated region. The study illustrates the potential to exploit spatially optimized phase transformations in a scalable manufacturing process of amorphous and nanocrystalline alloys to locally access otherwise inaccessible extreme heating and cooling rates.

Crystallization behavior and properties characterization for high-energy state FeSiBCuC metallic glass produced by strip casting

High-energy state Fe-based amorphous ribbons produced by twin-roll strip casting with significant thickness always suffer catastrophic coercivity (Hc) and annealing brittleness. The microstructure and property of the Fe78.9B11.8Si7.6C1Cu0.7 amorphous ribbon were investigated. After annealing with a high heating rate of 6 × 103 K/min, the saturated magnetic induction (Bs) of the twin-roll ribbon significantly improves, yet the Hc remains at an inferior level. However, compared with traditional annealing, a much lower Hc is obtained for twin-roll ribbons through multiple-rapid annealing (MRA). The improvement of soft magnetic property stems from various aspects. Due to completely released internal stress and smaller activation energy in MRA treated twin-roll ribbon, many fine α-Fe(Si) grains (20.7 nm) are precipitated on the amorphous matrix, significantly eliminating the magnetocrystalline anisotropy and neutralising the magnetostriction coefficient, reducing the Hc. On the other hand, fine α-Fe(Si) grains with volume fraction up to 80% are favorable to improve the Bs further. Besides, some shear bands appear in the fracture surfaces of MRA treated twin-roll ribbon, indicating that annealing brittleness can be restored to a certain extent. Finally, the twin-roll Fe78.9B11.8Si7.6C1Cu0.7 nanocrystalline alloy shows a high Bs of 1.72 T, low Hc of 6.2 A/m, and high hardness of 10.9 GPa by MRA treatment.

Revealing the effects of melt temperature on structure and magnetic properties in Fe–Si–B–C alloy

The effects of melt temperature in range of 1150–1400 °C on amorphous structure, magnetic properties and magnetic structures of Fe–Si–B–C amorphous ribbons were systematically investigated. The results of high-resolution transmission electron microscopy confirm that there exist a number of metastable nano-scales clusters in the quenched ribbons spinning at low melt temperature (1150 and 1300 °C). The measurement of flash differential scanning calorimetry finds that the thermal stability of the quenched ribbons notably increases with melt temperature elevating, also implying that higher melt temperature favors the higher degree of amorphization for the alloy. During the crystallization annealing process, the metastable Fe23(B, C)6 phase is preferentially precipitated at high melt temperature (1400 °C). The magnetic structure analyzed by magnetic force microscope reveals that a wide and uniform distribution of domain can be obtained in the alloy spun at high melt temperature (1400 °C), and that the domain size (width and length-breadth ratio of domain) is well correlated with coercivity and effective permeability. These current results provide important insights into the correlation between melt temperature and magnetic structure of Fe-based amorphous ribbons and are helpful to guide the production of Fe-based amorphous ribbons with homogeneous and stable amorphous structure from the technical level.

Improving the Bs and soft magnetic properties of Fe-based amorphous ribbons by manipulating the surface crystallization behavior

Improving the Bs and soft magnetic properties of Fe-based amorphous ribbons by manipulating the surface crystallization behavior

The effect of the thermal heating on the magnetic properties of a high permeability amorphous Fe76.5Cu1Nb3Si13.5B6 ribbon

In this work, the effects of the thermal heating on an as-cast Fe-based amorphous ribbon treated in a conventional furnace are reported. We used thermogravimetry, differential scanning calorimetry, X-ray diffraction and MvsH measurements to characterize the samples. The transition temperatures of magnetic phases (amorphous residual matrix and Fe3Si nanoparticles), which were estimated from thermogravimetric measurements, are thermal heat dependent. Besides, the analysis of the DSC data allows us to evaluate the crystallized fraction. From Rietveld refinement of the XRD diffraction patterns carried out after the DSC measurement, we confirm that the crystallized grains consist of Fe3Si (suessite) nanocrystalline phase. The suessite phases should be embedded inside the residual amorphous matrix. Furthermore, we synthesized a Fe3Si bulk sample using an arc furnace in order to compare its magnetic behavior with those Fe3Si nanoparticles. Finally, the magnetic anisotropy also shows to be thermal heat dependent.

Thermal, magnetic and mechanical behavior of large-sized Fe-based amorphous alloy ribbons by twin-roll strip casting

Fe-based amorphous alloys are characteristic of high saturation magnetization, low coercivity, and low core loss, which holds a grand promise for several engineering applications, such as soft magnetic, corrosion-resistant and wear-resistant coatings. However, poor amorphous forming ability (AFA) and size limit remain the main obstacles in applications. This study aims to address those scientific-technical challenges through a twin-roll strip casting method to yield two cost-effective Fe-based amorphous alloy (Fe73Mo4B5Si5P8C5 and Fe80Al2B5P9C4) ribbons with ca. 200-μm thickness and promising soft magnetic functions. Their crystallization behavior, thermal stability, magnetic properties, and mechanical performance for melt-spun and annealed alloys were studied systematically. Results demonstrate that Fe73Mo4B5Si5P8C5 and Fe80Al2B5P9C4 present good thermal stability, a large temperature interval between Tg and Tx1(61.7 °C for Fe73Mo4B5Si5P8C5 and 43.1 °C for Fe80Al2B5P9C4) infers that both the alloys have good processability. Meanwhile, Fe80Al2B5P9C4 amorphous alloy subjected to annealing at 450 °C for 300 s exhibited high saturation magnetization greater than 1.5 T, low coercivity of 5.3 A/m and high hardness of 989 Hv, which were attributed to the utterly amorphous structure and superior thermal stability achieved by twin-roll strip casting. Integrating the favorable mechanical, magnetic characteristics and high manufacturability of ultra-thick Fe73Mo4B5Si5P8C5 and Fe80Al2B5P9C4 amorphous alloys indicates that twin-roll strip casting is a sound solution to tackle the poor AFA and size limit in production of amorphous ribbons.

Study of Structure and Properties of Fe-Based Amorphous Ribbons after Pulsed Laser Interference Heating

The paper is devoted to the study of microstructural and magnetic properties of the Fe-based amorphous ribbons after interference pulsed laser heating. The ternary amorphous alloy FeSiB, as well as the multi-component alloys FeCuSiB and FeCuNbSiB, was subjected to laser pulses to induce crystallization in many microislands simultaneously. Structure and properties changes occurred in laser-heated dots. Detailed TEM analysis from a single dot shows the presence of FeSi(α) nanocrystals in the amorphous matrix. The FeSiB alloy is characterized after conventional crystallization by a dendritic structure; however, the alloys with copper as well copper and niobium additions are characterized by the formation of equiaxed crystals in the amorphous matrix. Amorphous alloys before and after the laser heating are soft magnetic; however, conventional crystallization leads to a deterioration of the soft magnetic properties of the material.