Nanocrystalline Soft Magnetic Iron-Based Materials from Liquid State to Ready Product

Цепелев, В. С.; Starodubtsev, Yu. N.

doi:10.3390/nano11010108

Cited by 23 publications

(23 citation statements)

References 122 publications

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“…These clusters are centers of nucleation of a large number of α-FeSi nanocrystals. Niobium inhibits the growth of the crystals to a higher temperature and provides a nanocrystalline structure with an average grain size of about 10 nm [ 4 ]. Instead of or together with Nb, other elements are used as inhibitors, for example, Mo, W, and V, which change the kinetics of heat release during crystallization [ 5 ] and contribute to obtaining the best magnetic properties during heat treatment of cores.…”

Section: Introductionmentioning

confidence: 99%

Permeability of Magnetic Cores with Air Gaps

Starodubtsev

Цепелев

Belozerov³

et al. 2022

Materials

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The influence of the geometric dimensions of the cut core and the number and size of air gaps on the effective permeability was investigated. Using dimensional analysis, an equation was obtained that relates the permeability of the cut core to the simplest dimensionless combination of the mean magnetic flux length l, single air gap length lg1, the cross-sectional area S of the core, and gap number ng. Permeability calculated from the geometric parameters of the cut core was compared with the effective permeability obtained using a two-dimensional FEMM simulation. Simulation has shown that the equation derived from dimensional analysis provides the best fit. The influence of each significant parameters l, lg1, ng, and S on cut core permeability is demonstrated. Experimental results have shown that an equation derived from dimensional analysis can be used to predict cut core permeability. In this case, one should take into account the residual air gap that forms after cutting the core. A method for assessing the residual air gap is proposed.

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Section: Introductionmentioning

confidence: 99%

Permeability of Magnetic Cores with Air Gaps

Starodubtsev

Цепелев

Belozerov³

et al. 2022

Materials

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“…The structure transition changes the chemical composition and size of the clusters and leads to a change in the activation energy. In the transition zone, the Arrhenius plot deviates from linearity and this anomaly can present a different shape [19]. On the other hand, the structure of the melt depends on the temperature and holding time, that is, on the heat treatment of the liquid steel.…”

Section: Introductionmentioning

confidence: 99%

Thermophysical Properties of Pipe Steel in the Liquid State

Цепелев

Starodubtsev

Tsepeleva

2021

Metals

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The temperature dependences of the kinematic viscosity and surface tension of liquid pipe steel with different modes of melt preparation were investigated. A transition zone was found on the temperature dependences of the thermophysical properties, which separates the regions with different activation energies of viscous flow and surface tension. At the heating stage in the transition zone, the thermal decomposition of clusters based on cementite Fe3C occurs. As a result of the decomposition, free carbon atoms appear which tend to give a uniform distribution in liquid iron with increasing temperature. At a low content of alloying elements and impurities, a high-temperature melt should have a large-scale cluster structure, which provides a more uniform distribution of chemical elements. The melt after vacuum degassing has a narrow transition zone near 1920 K, in contrast to the wide transition zone of the melt without vacuum degassing. The wider transition zone is shifted to high-temperature and this shift is associated with the thermal decomposition of carbides and oxides. Studies have shown that heating liquid pipe steel above the temperature of the liquid–liquid structural transition makes it possible to obtain a more homogeneous structure with a more uniform distribution of alloying and impurity elements in the melt. The sharp drop in surface tension at temperatures above 1920 K in the melt without vacuum degassing is associated with the diffusion of free S and O atoms, which are released after thermal decomposition of sulfides and oxides.

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“…From Equation (2) it follows that at a fixed temperature, the activation energy E a and the pre-exponential factor ν 0 are related to each other by the equation:…”

Section: Consequences Of Arrhenius Equationmentioning

confidence: 99%

“…Nanocrystalline soft magnetic materials are used for the manufacture of magnetic systems for various electrical devices [1]. The first and most widely used material was the classical nanocrystalline Finemet alloy with the chemical composition Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 [2]. To obtain special magnetic properties, the classical composition can be modified with various chemical elements Ni, Co, Mo, V, Cr and others.…”

Section: Introductionmentioning

confidence: 99%

Kinematic Viscosity ofMulticomponent FeCuNbSiB-BasedMelts

2021

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The work investigated the temperature dependences of the kinematic viscosity for multicomponent melts of nanocrystalline soft magnetic alloys. It is shown that there is a linear relationship between the reduced activation energy of viscous flow Ea·(RT)−1 and the pre-exponential factor ν0. This ratio is universal for all quantities, the temperature dependence of which is expressed by the Arrhenius equation. It is shown that the activation energy of a viscous flow is linearly related to the cluster size on a natural logarithmic scale, and the melt viscosity increases with decreasing cluster size. The change in the Arrhenius plot in the anomalous zone on the temperature dependence of viscosity can be interpreted as a liquid–liquid structure transition, which begins with the disintegration of clusters and ends with the formation of a new cluster structure.

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Nanocrystalline Soft Magnetic Iron-Based Materials from Liquid State to Ready Product

Cited by 23 publications

References 122 publications

Permeability of Magnetic Cores with Air Gaps

Permeability of Magnetic Cores with Air Gaps

Thermophysical Properties of Pipe Steel in the Liquid State

Kinematic Viscosity ofMulticomponent FeCuNbSiB-BasedMelts

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