Excellent Soft Magnetic Properties Research Articles

Electrodeposited NiFeCo + Tb and Dy for enhanced magnetostrictive properties and soft magnetism

Magnetostrictive thin films have numerous applications in communications, sensors, and microelectronic devices. Such devices usually require magnetostrictive thin films with large magnetostriction and soft magnetic properties. Nickel-Iron-Cobalt (NiFeCo) alloys can be easily fabricated as thin films in addition to having excellent soft magnetic properties. Their main drawback for these sensing applications is that they have very low magnetostriction. On the other hand, Iron-Rare Earth (RE) alloys such as Fe-Tb-Dy or Fe-Ga have large magnetostriction at the cost of some soft magnetic properties. Moreover, their magnetostrictive properties are degraded when reduced to thin films as opposed to bulk materials due to structural imperfections and oxidation of the REs. In this paper, we report the development of NiFeCo thin films with incorporated rare earth elements prepared via electrodeposition. Electrochemical cells were prepared using Ni,Fe, and Co sulfate salts. Tb and Dy sulfates were added to the electrochemical cell in order of increasing concentration. Electrodeposition was then carried out under galvanostatic control for each RE concentration in the bath. The produced films were analyzed for composition, crystallinity, and magnetic properties to draw out trends based on the initial concentrations of rare earth salts in the bath. The produced thin films retained soft magnetic properties while exhibiting giant magnetostriction of up to ∼370 ppm depending on the type and amount of incorporated REs within the film. The combination of soft magnetism and giant magnetostriction makes these NiFeCo thin films with added Tb and Dy excellent candidates for developing resonant frequency sensing devices.

Novel Fe–B–P–C–Cu–Co amorphous/nanocrystalline alloys with excellent comprehensive performance via Co substitution for Fe

The amorphous formation ability, thermal properties, crystallization behavior, magnetic properties, resistivity and bending ductility of Fe84.5-xB12P2C1Cu0.5Cox (x = 0, 4, 8) alloys were systematically investigated. It is found that the substitution of Fe by Co promotes the transformation of the as-spun alloys from a completely amorphous structure to an amorphous/nanocrystalline dual-phase structure, which is related to the differences in the interactions between the involved atoms. The saturation magnetization of alloys increases with increasing Co content and can be increased to 1.93 T at x = 8 by heat treatment, but excessive substitution of Co for Fe deteriorates the coercivity and bending ductility due to the pre-existing α-Fe(Co) grains. The resistivity is positively correlated with the disorder of structure, and the as-spun alloy with x = 4 exhibits a high resistivity of 136.2 μΩ cm. As a result, the annealed Fe80.5B12P2C1Cu0.5Co4 alloy with excellent soft magnetic properties (Ms = 1.81 T, Hc = 7.8 A/m) and good bending ductility in combination with high resistivity has potential for application in the field of electronic devices.

Potential of powder metallurgical methods to fabricate Fe-6.5Si soft magnetic components

The soft magnetic Fe-6.5Si alloy is well known for its excellent soft magnetic properties but its usage is limited due to fabricational constrains by conventional methods. Powder metallurgical processing of Fe-6.5Si is possible by a variety of different methods shown here, sinter-based screen printing (SP), electron beam powder bed fusion (E-PBF) and field-assisted sintering (field-assisted sintering/spark plasma sintering, FAST/SPS). The microstructure of the components varies strongly by process and powder used which is directly influencing their soft magnetic properties. The correlation between powder properties and processing parameters on the structural and magnetic properties is established. Lowest coercivity ( H c = 7 A m−1) is achieved by E-PBF due to large grain size minimising hysteresis losses necessary for direct current applications. SP can provide sheets with low coercivity ( H c = 21 A m−1) and adjustable thickness reducing eddy current losses especially suitable for alternating current application at higher frequencies. FAST/SPS can be used for a large range of powder particle sizes which is suitable to tune the soft magnetic properties in a wide range between 40 and 210 A m−1.

Effects of Cr addition on structure, magnetic properties and corrosion resistance of a Fe85.5B13Cu1.5 nanocrystalline alloy

The melt-spun structure of a Fe85.5B13Cu1.5 alloy was regulated by the addition of corrosion-resistant Cr with a moderate enhancement in amorphous-forming ability, which further refines the nanostructure and improves the soft magnetic properties and corrosion resistance of corresponding nanocrystalline alloys. The results show that high-number-density α-Fe grains in size of below 10 nm are formed in the amorphous matrix of melt-spun Fe85.5-xB13Cu1.5Crx (x = 0–6) alloy ribbons, and the grain size and number density gradually decrease with the increase in Cr content. After annealing, the α-Fe average grain size (Dα-Fe) and coercivity (Hc) of corresponding nanocrystalline alloys reduce significantly with increasing x from 0 to 3, and the reduction becomes less pronounced within x = 3–6, while the saturation magnetic flux densities (Bs) steadily decreases as x increases from 0 to 6. A Fe82.5B13Cu1.5Cr3 nanocrystalline alloy with the Dα-Fe of 14.9 nm possesses excellent comprehensive soft magnetic properties with the Hc and Bs of 13.8 A/m and 1.74 T, respectively. The fine nanostructure and good magnetic softness results from the optimum combination of pre-existing α-Fe competitive growth and Cr-inhibited atom diffusion. The nanocrystalline alloys show improved corrosion resistance in NaCl solution compared to their respective melt-spun precursors, and the addition of Cr further enhances the corrosion resistance. The alloyed Cr also reduces the annealing embrittlement of the nanocrystalline alloys.

Plastic deformation mechanisms of FeSiCrNi high silicon steel based on local canning compression

High silicon steel has excellent soft magnetic properties, but a poor plasticity limits its practical application seriously. In this research, a novel FeSiCrNi alloy short for Fe-6.5Si–2Cr–12Ni (wt%) was designed and deformed via the local canning compression process at room temperature. It was shown that the FeSiCrNi alloy presents a relatively high plasticity in a triaxial compressive stress state. Geometrically necessary dislocations ensure the compatibility of plastic deformation for FeSiCrNi alloy. There are a small number of η and γ textures inside the FeSiCrNi sample. The intensity of η texture nearly keeps steady, while the intensity of γ texture increases slightly with the level of plastic deformation increasing. Additionally, the intensity of {112}<111> copper texture increases with the increase of plastic deformation. Lath structures dominate the inhomogeneous plastic deformation of FeSiCrNi alloy and then integrate with the phase α-Fe. The main deformation mechanism of FeSiCrNi alloy is dislocation slip rather than twinning which has not been observed yet. The order degree of FeSiCrNi alloy continuously decreases, and deformation bands, dislocation walls and dislocation cells are successively formed, as the compression proceeds. It is feasible to produce FeSiCrNi components in cold forming process.

Influence of Annealing Process on Soft Magnetic Properties of Fe-B-C-Si-P Amorphous Alloys.

It is well known that the annealing process plays a key role in tuning the properties of Fe-based amorphous soft magnetic alloys. However, the optimal annealing process for a particular amorphous alloy is often difficult to determine. Here, Fe81.4B13.2C2.8Si1.8P0.8 and Fe82.2B12.4C2.8Si1.8P0.8 amorphous alloys (denoted as Fe81.4 and Fe82.2) were prepared to systematically study the effects of the annealing temperature and time on the soft magnetic properties. The results show that the optimum annealing temperature ranges of the Fe81.4 and Fe82.2 amorphous alloys were 623 K to 653 K and 593 K to 623 K, and their coercivity (Hc) values were only 2.0-2.5 A/m and 1.3-2.7 A/m, respectively. Furthermore, a characteristic temperature Tai was obtained to guide the choosing of the annealing temperature at which the dBs/dT begins to decrease rapidly. Based on the theory of spontaneous magnetization, the relationship between Tai and the optimum annealing temperature ranges was analyzed. When the annealing temperature was higher than Tai, the effect of the internal magnetic field generated by spontaneous magnetization on the relaxation behavior was significantly reduced, and the alloys exhibited excellent soft magnetic properties. It is worth indicating that when annealed at 603 K (slightly higher than Tai), the Fe82.2 amorphous alloys exhibited excellent and stable soft magnetic properties even if annealed for a long time. The Hc of Fe82.2B12.4C2.8Si1.8P0.8 amorphous alloys was only 1.9 A/m when annealed at 603 K for 330 min. This value of Tai is expected to provide a suggestion for the proper annealing temperature of other amorphous soft magnetic alloys.

Finemet nanocrystalline magnetic powder cores: Application of binder and warm compaction process

In this paper, Finemet flake amorphous powder with poor flowability is used as raw material to investigate the effect of the type of silicone resin and compaction method on the density and soft magnetic properties of the magnetic powder cores. The results show that due to the different thermal stability of the three silicone resins 600, S2 and JH, the permeability of the three magnetic powder cores has significant differences. Since the lubricant is in a viscous flow state during the warm compaction and reduces the friction between the particles, the density of the magnetic powder cores is increased, which further improves the soft magnetic properties of the magnetic powder cores. Among them, the density of Finemet magnetic powder cores prepared by warm compaction with the S2 silicone resin as binder is 5.62 g∙cm−3, the permeability is 43.86, the DC bias capability is 66.77 % at 100 Oe, and the total loss is 113.94 mW∙cm−3 (100 kHz, 50 mT), which has excellent comprehensive soft magnetic properties and is a very significant improvement compared with cold compaction. This shows that the warm compaction process is an effective method to further improve the soft magnetic properties of magnetic powder cores.

Effect of trace Nb element on the performance of Fe82-xB10P7.5Cu0.5Nbx amorphous/nanocrystalline ribbons by one-step melt spinning method

The amorphous/nanocrystalline duplex structure is a stable structure with excellent soft magnetic properties, but there is still very little research on the amorphous/nanocrystalline alloy obtained by one-step melt spinning method. In this work, Fe82-xB10P7.5Cu0.5Nbx (x = 0, 0.5, 1.0, & 1.5 at%) alloys whose performance can surpass Fe-Si-B alloy was prepared, and the effect of trace Nb element replacing Fe element on the structural characteristics, thermal properties, mechanical properties and soft magnetic properties of the alloys were studied. With the increase of Nb content, the saturation magnetic flux density of the alloys gradually increases. The Fe81.5B10P7.5Cu0.5Nb0.5 shows a saturation magnetic flux density of 1.68 T and a coercivity of 5.56 A/m, together with stable thermal properties and good mechanical properties, which provides a promising candidate for amorphous/nanocrystalline alloys with both excellent soft magnetic properties and satisfactory processing properties.

XGBoost algorithm-assisted prediction of amorphous formability of Fe-based nanocrystalline precursor

The completely amorphous structure in the precursor is a significantly important prerequisite for obtaining the perfect amorphous-nanocrystalline duplex structure and the excellent soft magnetic properties of Fe-based nanocrystalline alloy ribbons (FNR). However, the correlation between the amorphous formability (AFA) and the key parameters of FNR precursors is not clear. Herein, a data-preprocessed dataset was established, consisting of 158 FNR samples with amorphous and crystallized precursors. This dataset includes features such as elements, thermal parameters, and calculated parameters. Pearson correlation analysis was performed to assess the linear correlation between any two features, resulting in the removal of eight features. Then the features importance was ranked by random forest (RF) algorithm, and top five key features (e.g., ΔT, VEC1, VEC, P, and B) were retained. A classification predictive model in that the structure of FNR precursors is amorphous or crystalline was constructed based on XGBoost algorithm. The accuracy of the classification model by confusion matrix analysis is up to 97.9 %. Furthermore, SHAP (SHapley Additive exPlanations) results reveal that crystallization temperature intervals (ΔT), valence electron concentration without Fe, Ni, and Co elements (VEC1), as well as valence electron concentration (VEC) play an important role in affecting AFA of FNR precursors. When ΔT > 142 °C, VEC1 > 0.69, and VEC >7.27, the FNR precursors readily obtain a fully amorphous structure. The outstanding classification accuracy and the elucidated correlation between the key features and AFA could guide the discovery of novel fully amorphous FNR precursors.

Soft magnetic properties of Fe-Ni powder cores in the high frequency range

Fe-Ni cores are excellent candidates for switching regulator inductors, transformers, reactors and in-line noise filters. Herein the influence of the phenol binder content on the microstructure and magnetic properties of Fe-50 wt% Ni powder cores in the high frequency range is investigated. Regardless of the binder content, all cores form a disordered A1 phase. The saturation magnetization (4πMs) and initial permeability increase as the binder content decreases. The core with a binder content of 0.5 wt% shows a relatively high 4πMs of 1.38 T and the highest permeability value of 70.9. Moreover, the total core loss (Pcv) with frequency ranges from 5 kHz to 1 MHz under a magnetic flux density of 10 mT depending on the binder content. A binder content of 3.0 wt% significantly reduces Pcv in the high frequency range above 100 kHz. At a frequency of 500 kHz, the Pcv values are 154.9, 128.7, and 133.8 kW/m3 for the cores with binder contents of 0.3, 0.5, and 1.0 wt%, respectively, but the value drastically decreases to 60.5 kW/m3 for a binder content of 3.0 wt%. Thus, the binder, which acts as an insulator layer between particles, affects the eddy current and consequently, Pcv. These results demonstrate that Fe-Ni powder cores exhibit excellent soft magnetic properties at various frequencies and suggest that a binder content of 3.0 wt% may realize optimal properties for future high frequency applications.

Effect of Mn content on crystallization behaviors and magnetic properties of FeCoNiBMn high-entropy amorphous alloys

FeCoNi-based high-entropy alloys (HEAAs) attracted much attention because of their good thermodynamic stability, mechanical properties and soft magnetic properties. In this paper, Fe22Co22Ni22B34-xMnx (x = 6–22 at%) HEAAs were designed and the effects of Mn on the crystallization behaviors, magnetic performance, and mechanical property were investigated. The crystallization behaviors of the FeCoNiBMn HEAAs are: 1) 12–16 at% Mn: am → am’ + M23B6 → M23B6 + fcc; 2) 18 at% Mn: am → am’ + bcc + M23B6 → bcc + M23B6 → fcc + M23B6; and 3) 20–22 at% Mn: am → am’ + bcc → bcc + M23B6 → fcc + M23B6. Two parameters ΩA and VEC are proposed to predict the primary precipitates of FeCoNi-based HEAAs. All as-spun ribbons exhibit excellent soft magnetic properties with a very low coercivity (Hc) of less than 1.5 A/m and a maximum saturation magnetization (Bs) of 0.82 T. The 14 at% Mn alloy exhibits very low Hc of less than 4 A/m even after complete crystallization. Magnetic properties and Vickers hardness of crystalline ribbons are closely related to crystallization behaviors.

A Smart Amorphous Wire Composite with Tunable Electromagnetic Shielding

Nowadays, in view of the increasingly serious problems of electromagnetic interference (EMI) and radiation pollution, smart EMI shielding materials with tunable shielding effectiveness (SE), especially “On/Off” switchable capability, are highly desirable. Herein, Co‐based amorphous wires (AWs) with excellent soft magnetic and mechanical properties are regularly arranged on a 3D‐printed mold as tunable EMI shielding composites. The EMI SE can be easily tuned in the range of ≈0.6–24.7 dB by way of rotation, which has been confirmed to be an effective way to achieve free tuning of EMI SE by simulation. In addition, by compositing AWs with reduced graphene oxide and constructing a double‐layer structure with a gap of 1/4 wavelength in the X‐band, a much wider SE tuning range of ≈1.0–57.7 dB is further realized. The representative “On/Off” switchable shielding capability that can switch between EM transmission and effective shielding, together with the wide SE tuning range larger than 50 dB, shows the great potential of Co‐based AW composites in smart EMI shielding applications.

The effect of phosphate/TiO2 composite insulating layer on the high frequency magnetic properties of FeSiBPCNbCu nanocrystalline soft magnetic powder cores

Currently, power electronic devices are developing to meet the requirement of miniaturization, high-frequency and low-power consumption, reducing the high-frequency loss of soft magnetic powder cores (SMPCs) is one of the popular research topics. The construction of multilayer insulating structures can reduce the core loss (Pcv) of SMPCs by increasing the resistivity. In this work, a composite inorganic insulating layer of phosphate and TiO2 was successfully synthesized on the powder surface by phosphating and then sol-gel method. At last a nanocrystaline SMPCs with excellent soft magnetic properties were prepared with epoxy resin as the binder. The cores were heat-treated at 510 ℃ for 1 h to achieve optimum soft magnetic properties, with a low Pcv of 854 mW/cm3 at 20 mT and 2 MHz, an effective permeability (μe) of 40 at 10 MHz and excellent DC bias with a percent permeability of 74% of the initial value at 100 Oe. The synergistic effect of the epoxy - TiO2 - phosphate - nanocrystalline powder multilayer interface effectively reduces inter-particle eddy current loss, resulting in a significant reduction in the Pcv of the SMPCs.

Influence rules of early transition elements on rapid solidified structure and nanocrystallization behaviors of Fe-Si-B-Cu soft magnetic alloys with high Cu content

Unique rapid solidified structure and nanocrystallization mechanism enable the Fe-based nanocrystalline alloys with high Cu content excellent soft magnetic properties and good manufacturability, and also results in unusual phenomena in terms of alloying effects. In the present work, we systematically studied the influence rules of early transition elements on the rapid solidified structure and nanocrystallization behaviors of Fe-Si-B-Cu soft magnetic alloys with high Cu content and explored the related mechanisms. In terms of rapid solidified structure, the additions of early transition elements always inhibit the formation of pre-existing α-Fe crystals even eliminate them, and the additions that could produce larger atomic mismatch parameter (δ) and negative mixing enthalpy (ΔHmix) show stronger effects. In terms of nanocrystallization behaviors, the increases in δ and negative ΔHmix weaken the competitive growth between the pre-existing nanocrystals during annealing and then coarsen the nanostructure of the annealed alloys and deteriorate their magnetic softness, while the excessive increases in δ and negative ΔHmix could significantly suppress the growth of α-Fe crystals by diffusion inhibition during annealing and thus remarkable refine the nanostructure of the annealed alloys and improve their magnetic softness.

Efficient property-oriented optimization of magnetic high-entropy metallic glasses via a multi-stage design strategy

High-entropy metallic glasses (HE-MGs) have drawn much attention as promising multifunctional materials combining the excellent soft magnetic properties of traditional metallic glasses and impressive mechanical properties, thermal stability, corrosion resistance, etc., of solid solution high entropy alloys. Property optimization of HE-MGs is of great significance for promoting their engineering applications. However, various constituent elements and the high chemical complexity make the possible alloying composition space extremely massive, which is very challenging for the rational design of HE-MGs. In this work, we proposed a multi-stage optimization strategy based on machine learning (ML) to accelerate the rational design of magnetic HE-MGs with desired properties. The huge composition search space was significantly narrowed by the ML-based phase prediction model and constraints from user preferences. Utility functions based on the exploitation and exploration strategy were designed to find the global optimization solutions, i.e., alloying compositions. Experiments were conducted as concept validation, and new Fe-Co-Ni-Si-B HE-MGs with balanced saturation magnetic flux density and mixing entropy were developed.

Magnetic property regulation and mechanism analysis of FeSiBC soft magnetic composites by mixing with FeSiCr or carbonyl iron powder

FeSiBC, FeSiCr, and CIP (carbonyl iron powder) are the main raw materials for the preparation of molding choke. In this study, water atomized FeSiCr powder with three particle size groups and CIP with a fixed particle size were used as raw materials to explore the influence of fine powder size and type on soft magnetic properties of FeSiBC SMPCs (soft magnetic powder cores). The results show that by adding a certain proportion of FeSiCr fine powder, the pores between large-size FeSiBC amorphous powder could be effectively filled, so that the density and permeability of SMPCs increased monotonically with the increase of FeSiCr content, while the porosity and DC bias performance decreased monotonically. In addition, the smaller the particle size of the FeSiCr, the more beneficial it was to reduce the eddy current loss of SMPCs. In the mixed FeSiCr scheme, adding 10 wt% FeSiCr with an average particle size of 6 μm was the best. In this case, the permeability of SMPCs was 18.01 and the core loss was 239.15 mW·cm−3 (100 kHz, 50 mT). Compared with hard FeSiCr, the deformation of CIP was greater during the pressing process due to its extremely low hardness, which could effectively fill the pores of SMPCs, thus greatly improving the comprehensive performance. The FeSiBC/30 %CIP SMPCs prepared in this study had excellent soft magnetic properties (permeability of 26.26, DC bias performance of 94.58 % at 100 Oe and core loss of 192.10 mW·cm−3 at 100 kHz and 50 mT), highest strength (6.54 ± 0.08 MPa) and lowest cost (13.7 $∙kg−1), and the comprehensive performance was significantly better than that of FeSiBC/FeSiCr SMPCs with different particle sizes. It can be seen that mixing FeSiBC amorphous powder with a small amount of powder that has a significant difference in hardness and particle size and complementary soft magnetic properties is an effective way to improve the magnetic properties of SMPCs.

Unusual gradient stress induced superior room-temperature plasticity in brittle ferromagnetic bulk metallic glass

Ferromagnetic bulk metallic glasses (FBMGs) possess excellent soft magnetic properties, good corrosion resistance, and high strength. Unfortunately, their commercial utility is limited by their brittleness. In this work, we report the enhancement in the room-temperature plasticity during the compression (25%) and bending flexibility of Fe74Mo6P13C7 FBMG by using water quenching. The high-energy synchrotron X-ray measurements, high-resolution transmission electron microscopy, three-dimensional X-ray microtomography, and finite element simulation were performed to reveal the origin. It was found that the M-shape profile of residual stress improves the mechanical properties of FBMGs, particularly their plasticity. The reversal of the heat-transfer coefficient and cooling rate from the ‘vapor blanket’ to ‘nucleate boiling’ transition during water quenching processing is the main cause of the unusual profile of residual stress in glassy cylinders. Encouraged by the progress in developing flexible silicate glasses, this work highlights a processing method to improve plasticity and surmount technical barriers for the commercialization of FBMGs.

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.

An in-situ formed TiC/FeCoNi medium-entropy composite with excellent combination of mechanical and soft magnetic properties

The utilization of conventional Fe–Co soft magnetic materials (SMMs) as essential materials in electric motors and electromagnets is well-established, however, their mechanical properties cannot be further improved. In order to achieve an excellent balance between mechanical and soft magnetic properties, a novel FeCoNi-based medium entropy composite (MEC) reinforced with in-situ synthesized TiC was designed and prepared via mechanical alloying (MA) and spark plasma sintering (SPS). After the SPS process, the developed MEC exhibited a heterogeneous microstructure consisting of ultra-fine face-centered cubic (FCC) grains, micron-sized FCC grains and in-situ nanosized particles. This resulted in exceptional mechanical properties, with a high tensile yield strength of 910 MPa, combined with a total elongation of 10.9%. The superior mechanical properties of the MEC were attributed to dispersion strengthening, hetero-deformation induced (HDI) strengthening and solid solution strengthening. Additionally, the TiC/FeNiCo MEC also exhibited excellent soft magnetic properties, displaying a high saturation magnetization of 141 emu/g and low coercivity of 619 A/m. Therefore, these results demonstrate the potential of the developed MEC to serve as a promising soft magnetic material (SMM) for future applications.

Tailoring the thermal stability and soft magnetic properties of Fe80-xNixSi7B8P4Cu1 amorphous nanocrystalline alloys based on the magnetic domain structure

Structure, crystallization behavior, dynamic domains, and magnetic properties of as-quenched and annealed Fe80-xNixSi7B8P4Cu1 (x = 0, 1, 2, 3 and 4) alloy ribbons have been investigated. It finds that the partial substitution of Ni for Fe promotes the formation of amorphous structure. We have determined the critical spinning speed for the formation of pre-existing α-Fe cluster structures. In addition, a little increase in Ni content effectively inhibits the excessive growth of the α-Fe grains, which contributes to the reduction of grain size and Hc. Moreover, the role of Ni on the magnetic domain structures and its correlation medel was established. After proper annealing treatment, the Fe79Ni1Si7B8P4Cu1 nanocrystalline alloy exhibited excellent soft-magnetic properties including a high Bs of 1.58 T, a low Hc of 2.48 A/m and a high μe of 16400, which is closely related to the high volume fraction of α-Fe grains and uniform refinement of magnetic domains which is more conducive to the migration and rotation of magnetic domains.