Soft magnetic composites (SMCs) are essential for electromagnetic devices requiring high electrical resistivity and low magnetic losses. The current demand for cost-effective and energy-efficient materials drives research to enhance their characteristics towards more sustainable solutions. Fe@MgO composites were prepared by dry particle coating and subjected to microwave heat treatment at 600 degrees C with varying MgO contents (2-5 wt%), Both preparation techniques represent the progressive - ecologically and economically beneficial ones. Microstructural analyses revealed the formation of a non-stoichiometric magnesia-ferrite spinel interphase. Increasing MgO content decreased elastic moduli and permeability while enhancing electrical resistivity and coercivity, affecting magnetic domain wall movability and losses. Microwave-treated composites exhibited improved complex permeability and frequency stability compared to conventionally treated samples, indicating a presence of a ferrimagnetic phase as well, which enables magnetic flux continuity at the insulation layer. Notably, 2-3 wt% MgO yielded low DC hysteresis losses and higher permeability, whereas 5 wt% MgO optimised AC losses and DC-bias stability (similar to 80% at 40 Oe). These findings demonstrate that microwave processing effectively tailors microstructure and magnetic properties, offering a versatile approach to optimise Fe@MgO SMCs for specific electromagnetic applications.

Soft magnetic composites (SMCs) based on iron powders insulated with alumina $(\text{Al}_{2} \mathrm{O}_{3})$ are promising materials for electromagnetic applications requiring low magnetic losses and isotropic magnetic behavior. This study investigates the influence of mechanofusion processing time and $\text{Al}_{2} \mathrm{O}_{3}$ content on the microstructure and magnetic properties of Fe-based SMCs. Two series of samples were prepared using different dry coating durations (15 min and 30 min) and varying $\text{Al}_{2} \mathrm{O}_{3}$ weight fractions $(2-15 \text{wt}. {\%})$. Microstructural characterization was performed using SEM and EDX mapping, while magnetic behavior was evaluated through hysteresis loss measurements as a function of maximum magnetic induction. The results demonstrate that shorter mechanofusion duration leads to reduced hysteresis losses. These findings highlight the importance of optimizing mechanofusion parameters for tailoring magnetization processes and improving the performance of iron-based SMCs.

This study investigates how compaction pressure and die shape influence the density distribution and related magnetic and electrical properties of pure iron based green compacts. By combining empirical densification models with geometry-specific corrections for wall friction and shear deformation, numerical simulations were conducted for three die types: cylindrical, prismatic, and ring. The simulations predict spatial variations in densification that align with experimental observations from optical microscopy. Results show that high compaction pressures (up to 2500 MPa) can enhance magnetic performance by increasing density and reducing porosity, but they also cause significant inhomogeneities, especially in cylindrical shapes, due to stress localisation near die walls. Ring-shaped compacts demonstrate better uniformity in both density and magnetic properties, confirming the importance of geometry-dependent modelling of compaction. Surface flash formation and grain deformation at the die-punch interface align with shear-enhanced densification zones forecasted by the model. Overall, the findings emphasise the need to consider both friction and shear effects when designing powder metallurgy processes for soft magnetic materials.

Soft magnetic composites are nowadays the subject of intensive research. Due to their high electrical resistance and relatively high permeability values, these materials have a vast application potential. The aim of this work was to investigate the effect of increasing Ni-Zn-Cu soft magnetic ferrite content added in Fe@SiO2 soft magnetic composite samples on the permeability and energy loss. We examined samples containing 0, 2, 5, 10, 20, and 30 volume percentages of ferrite powder. The energy loss separation into high and low induction losses was performed. The energy losses of samples with 2% and 5% of ferrite powder below 0.55 T can be attributed almost solely to domain wall displacements. These samples also possess the highest values of the real part of complex permeability with high frequency stability. We found, that adding small amounts (2-5 vol%) of ferrite powder into Fe@SiO2 SMCs enhances their magnetic properties.

The study investigates the effects of the ratio of the Fe/FeSi , the different process additives and compaction parameters, on the magnetic properties of Fe-6.5Si/Fe@phosphate soft magnetic composites (SMCs), obtained by a method of mixing different commercially used powder materials. With the world's rapid advancement in 5G and the development of 6G mobile communications, robotics, and the emerging new applications, such as electric vehicles, or the renewable energy industries, such as photovoltaic technology, the soft magnetic materials components for power and electronic devices operating at high frequencies toward megahertz range and beyond, are urgently required. The goal of improving the high-frequency characteristics of the resulting composites while concurrently maintaining their cost-effective mass production capability was fulfilled, and the compositions with a significantly enhanced frequency stability of magnetic permeability were found (e.g., for a 50/50wt.% ratio: a stable real part of complex relative permeability of similar to 65 , the resonant frequency of similar to 1MHz ). The relatively low core energy losses ( similar to 80 J/m(3) at 1kHz,0.2 T ) are ensured by a sufficiently high specific resistivity ( similar to 0.1 Omega & sdot; cm ), the values comparable with the current literature ones. The assessment of magnetic and electrical properties indicates the effective insulation of ferromagnetic particles, and the inorganic insulation; furthermore, it enables the Fe-6.5Si powder to be used as a ferromagnetic component for composites intended also for higher temperature applications.

Iron-based soft magnetic composites (SMCs) insulated with Al₂O₃ are promising for electromagnetic applications requiring low magnetic losses and isotropic magnetic behavior. This study investigates the effect of dry coating processing duration (15 min and 30 min) and Al₂O₃ content (2 wt.% - 15 wt.%) on the microstructure and magnetic properties of ring-shaped Fe@Al2O3 SMCs. Microstructural analysis by SEM and EDS confirmed the distribution and clustering of Al2O3 at iron particle interfaces, while magnetic characterization included coercivity, hysteresis loss and their separation, frequency-dependent total energy loss and complex permeability. The results show that shorter dry coating times preserve higher permeability and lower losses, whereas longer dry coating times improve the permeability cut-off frequency but increase coercivity and reduce permeability, especially at higher Al2O3 contents. These findings demonstrate that both Al2O3 content and dry coating time are critical for optimizing the trade-off between loss minimization, permeability, and high-frequency performance in iron-based SMCs.

This study examines the influence of microwave (MW) heating parameters on the structure and electromagnetic properties of soft magnetic composites (SMCs) based on Fe-6.5 wt%Si particles with a lithium-alumina-borate (LAB) ceramic insulator. MW annealing at 2.45 GHz was applied under varying durations, with and without a SiC susceptor, to evaluate the combined effects of FeSi particle size and sintering conditions. Longer MW sintering results in higher resistivity, with larger FeSi particles exhibiting the highest resistivity values. Coercivity decreases with increasing FeSi particle size, with longer sintering times only slightly affecting samples containing larger particles. Complex permeability analysis shows a complex relationship with FeSi particle size, where larger particles generally have higher permeability, but relaxation frequency varies with particle size and sintering conditions. Microstructural analysis reveals a thin LAB ceramic layer formed between FeSi particles, with LAB concentration in inter-particle regions influenced by particle size and contributing to the MW heating and sintering process. The presence of a liquid phase was observed in the microstructure, influenced by the presence of a SiC susceptor and FeSi particle size. Optimal properties, initial permeability of 73, relaxation frequency of 467 kHz, and resistivity of 0.035 Omega cm, were achieved with 268 mu m FeSi particles sintered for 60 min using a SiC susceptor. These findings highlight the critical role of particle size and MW parameters in tailoring SMC performance and provide guidance for the development of advanced magnetic materials.

Building upon previous studies that have reported promising soft magnetic performance of Fe/Mn-Zn ferrite-based soft magnetic composites (SMCs), the present work focuses on effect of ferrite content and temperature on the magnetic properties of Fe@SiO2@Mn-Zn-ferrite SMC materials. A series of five Fe/SiO2/Mn-Zn SMCs were fabricated using powder metallurgy and compaction. Structural characterization and detailed magnetic property measurements were performed to assess their soft magnetic behavior. The composites were synthesized with varying mass ratios of Fe/SiO2 to Mn-Zn ferrite powders, specifically 100:0, 99:1, 98:2, 97:3, 96:4, and 90:10. Key magnetic parameters evaluated included complex permeability, maximum permeability, total core loss, and its components: hysteresis loss, classical eddy current loss, and excess loss. Furthermore, frequency-temperature loss maps were constructed to evaluate the magnetic performance under different thermal and frequency conditions. Considering the specific operational frequency requirements, the optimal ferrite concentration within the composite was determined to be in the range of 2-4%. The investigation highlighted the influence of excess magnetic losses, especially within the medium-frequency range. The modified composites demonstrated improved thermal stability, retaining favorable soft magnetic properties after thermal cycling up to 200 °C. These results highlight the potential applicability of the developed composites in environments demanding reliable high-temperature magnetic performance.

This paper presents the results of a study on the impact of variable compaction pressures on the magnetic properties of the developed compacted powder cores with the aim to determine the optimal compacting pressure for minimizing the power loss and improves frequency stability of permeability. We study the change in the shape of hysteresis loops and their effect on the values of hysteresis model parameters of the phenomenological GRUCAD model. The ball milling process and the compaction process generate mechanical stresses. We assume that there are two effects of the compaction pressure: a positive effect of reducing porosity and a negative effect of increasing mechanical stress inside the powder particles. It is shown that within the specified pressure range, there is a balance between the two determining factors, and the optimal pressure for power loss is 1.4 GPa and for frequency stability of the permeability is 1.5 GPa.

The present work describes the process of the creation and analysis of the first dataset containing processing parameters and functional properties of soft magnetic composites (SMC). All data were obtained experimentally using Fe-3% MgO system. When creating samples, parameters such as a size of MgO nanoparticles, pressing pressure, sintering temperature, time and atmosphere were varied. In total, 282 samples with a unique combination of processing parameters were obtained. In each sample, density, real part of complex magnetic permeability at different frequencies, coercivity, and resonant frequency were measured. This allowed us to create the first experimentally obtained dataset devoted to SMC. Such dataset is necessary for implementing data-driven research in the field of SMCs, as well as for studying correlations in the chain: processing parameters - structure - properties. The dataset is currently being expanded both in terms of expanding the set of variable independent parameters and in terms of expanding the set of controlled properties. The dataset is hosted in Figshare open repository.

Soft magnetic composites Fe/SiO 2 /Mn-Zn ferrite with low energy losses and high magnetic permeability are studied. The electromagnetic properties in composites with (a) 0 wt%, (b) 1 wt %, (c) 2 wt %, (d) 3 wt %, (e) 4 wt %, and (f) 10 wt % of ferrite are investigated. Further, loss separation as a function of ferrite content and temperature was studied. An increase in temperature in working conditions affects the magnetic properties of the SMCs, which requires consideration of the temperature effect in the process of predicting magnetic properties. The content of ferrite plays a significant role in modulating the magnetic properties of Fe/SiO 2 /ferrite soft magnetic composites. The effect of the presence of the SiO 2 layer can play the positive role after the thermal cycles to keep the unchanged structure.

Electrical steel's magnetic properties in industrial applications often differ from theoretical predictions due to assembly-induced mechanical stresses. In this study, we evaluate the impact of compressive stress applied perpendicular to the core on the magnetic behavior of structures crafted with an innovative approach. Utilizing shifted grain-oriented Fe-Si steel rings, the strategy effectively alleviates magnetic losses and mitigates magnetostriction-related vibrations. Insights into complex magnetization processes are revealed through the analysis of first-order reversal curves (FORC), demonstrating stress-induced alterations in hysteresis loops and FORC diagrams. Under the applied stress, an additional magnetization process emerges at low magnetic fields, resulting from domain reorganization and interacting with the effects introduced by shifting the layers within the core.

The study aims to evaluate the influence of surface modification of Fe powder on the magnetic behavior of soft magnetic compacts and composites that can possibly enhance their properties. The smoothing of ferromagnetic particle surfaces led to a decrease in the total energy loss as the most evident positive impact in all investigated classes (max. by 11

The transition from the traditional “post-analysis” strategy for developing soft magnetic materials to an innovative “pre-design” one is highly desirable for the development of advanced electrical devices. In this work, we present the creation of a machine learning (ML) model capable of accurately predicting the soft magnetic properties (JS, HC, μ, ρ) of Fe–Si–Al alloys based on their composition. Through extensive ML experiments employing various algorithms commonly utilized in ML-assisted materials science, including SVM, RFR, KNR, XGB, and others, we achieved high accuracy in predictions, as indicated by R2 values close to 1. The best models were used to predict the properties of the 22800 FeSiAl alloys with the Al and Si content up to 15 wt % and step 0.1 %. Out of this vast compositional space, five alloys were selected for experimental validation, demonstrating the high quality of the predictions. The performance of ML models for specific properties is analyzed in terms of the nature of the distribution of the data used for training. In addition, some composition-properties correlations in the Fe–Si–Al system were analyzed and discussed.

Soft magnetic iron finds practical use in many applications, such as electromagnets and relays. In order for these devices to work effectively, it is necessary to know their DC magnetic properties. Soft magnetic compacted powder cores possess lower permeability than powder particles from which they were prepared due to the inner demagnetization factor caused by the existence of pores in the core structure. The aim of the work was to determine the effect of surface mechanical treatment of iron powder particles of two different size fractions, leading either to an increase in the demagnetization factor or to a positive effect on the DC magnetic properties of the resulting compacted cores. For samples prepared from smaller powder particles, we found that despite the increase in inner demagnetization factor as a result of the smoothing procedure, the differential relative permeability increased, and total energy loss decreased.

The paper presents the analysis of the magnetic behaviour of soft magnetic powder compacts vs. the increasing compacting pressure. An unexpectedly positive result was obtained at a pressure of 1500 MPa, as the pure iron compact without coating of powder particles and without subsequent heat treatment showed very good magnetic properties compared to the class of soft magnetic composites (SMCs). In particular, the effective relative permeability of mu(eff) similar to 120, stable up to a frequency f similar to 200 kHz, the maximum total relative permeability of mu(max)(tot) similar to 700, and the specific electrical resistivity of rho(R) similar to 10(-5) Omega m. This phenomenon was explained on the basis of analyses of the samples microstructure, the magnetic and electrical properties, magnetization processes, inner demagnetizing fields, Barkhausen noise and thermal diffusivity. It was found that the grain size refinement inside iron particles occurs at certain elevated compaction pressure because the deformation bands gradually rise and break up with compaction pressure, leading to a higher resistivity of the compact thus to its SMC-like behaviour, despite the counteracting effect of increasing number of iron-iron bridges among neighbouring particles. The grain size refinement causes also the refinement of magnetic domain structure, which facilitates the magnetization reversal, although, the increased internal stresses and microstructural defects affect domain wall mobility negatively. The most favourable combination of the mentioned factors influences, finally resulting in the soft magnetic properties enhancement, appeared at 1500 MPa. Due to high-pressure compaction, the high density (above similar to 95 % of iron density) of a compact was achieved, ensuring sufficient mechanical properties. The presented material can serve as a potential supplanter of SMCs in many applications as it provides evident advantages, such as its easy production with minimum chemical waste (because any additional chemical processes and substances needed for particle coatings in conventional SMCs are completely omitted), as well as easy recycling process, which makes it eco-friendly and cost-effective, nevertheless, maintaining the advantages of SMCs.

Soft magnetic ferromagnetic/insulator composites are complex objects in terms of structure and magnetic properties. They depend on many different parameters, among which one of the main ones is the amount of insulator. In this work, the effect of MgO content on magnetization processes in Fe/MgO composites is studied in detail by using a wide combination of properties and structure analysis methods. Several series of samples with content steps up to 0.1 wt % were prepared using standard powder metallurgy operations such as dry mixing, cold pressing, and sintering. The study demonstrates that the evolution of Barkhausen noise with increasing MgO content is not systematic. The second phase acts as an effective barrier to magnetic interaction between neighboring Fe particles only after reaching a certain point, which was found to be about 0.9% wt. Some other properties (coercivity, permeability, elastic properties) also demonstrate nontrivial composition dependence. To reveal the causes of the observed phenomena, the structure of the composites was studied in detail, and it was shown that with an increase in the MgO content in the range of 0.8-1%, a change in the mechanisms of structure formation occurs, which, in turn, affects the properties. The presented results provide insights into developing advanced soft magnetic composites with an optimal combination of a ferromagnetic powder and an insulator.

Soft magnetic composites Fe/SiO 2 /ferrite with low energy losses and high magnetic permeability are studied. The magnetic properties in composites with (a) 0 vol%, (b) 2 vol%, (c) 5 vol%, and (d) 10 vol% of ferrite at peak induction of 0.1 T are investigated in the temperature range of 20–140 °C. Further, loss separation as a function of ferrite content and temperature was studied. An increase in temperature in working conditions affects the magnetic properties of the SMCs, which requires consideration of the temperature effect in the process of predicting magnetic properties. The content of ferrite plays a significant role in modulating the magnetic properties of Fe/SiO 2 /ferrite soft magnetic composites.