Magnetization Processes In Ferromagnetic Materials Research Articles

Effect of magnetic field on macroscopic hysteresis and microscopic magnetic domains for different ferromagnetic materials

The macroscopic hysteresis of ferromagnetic materials is influenced by their microscopic magnetic domains, establishing a correspondence between the two that enables a fundamental understanding of the magnetization process of ferromagnetic materials. Based on this, this study employs the phase field method to investigate the macroscopic hysteresis and microscopic magnetic domain evolution of soft, hard, and rectangular ferromagnetic materials. The hysteresis loops of the three materials present narrow, wide and rectangular characteristics respectively, which are quantitatively consistent with the experimental data. Subsequently, the influence of the magnetic field on the macroscopic hysteresis is analyzed. The results show that the hysteresis loop area increases when the magnetic field amplitude increases. Furthermore, the proportion of each type of energy under different magnetic fields is discussed, the dominant energy terms are generally consistent for the same category of ferromagnetic materials. Additionally, the corresponding magnetic domain evolution under different magnetic field is displayed, with soft magnetic materials exhibiting no vortex structures, hard ferromagnetic materials presenting a 45° vortex structure, and rectangular magnetic material showcasing a 90° vortex structure. Finally, the asymmetric characteristics of the major hysteresis loop and minor hysteresis loops are discussed. The change of the magnetic field path leads to the corresponding change of the major and minor hysteresis loops. At the same magnetic field, distinctions in magnetic domain configurations between the major and minor hysteresis loops are evident.

Estimation method of yield strength of ferromagnetic materials based on pulsed eddy current testing

In the current production of iron and steel industry, the testing of mechanical properties of ferromagnetic materials relies on tensile testing, which is time-consuming and destructive, thus greatly increasing the production cost. In order to solve this problem, a method based on pulsed eddy current is proposed to estimate the yield strength of ferromagnetic materials. Eddy current loss and hysteresis loss are the sources of loss in the magnetization process of ferromagnetic materials. Not only the loss but also the yield strength of the material is related to the microstructure of the magnetized material. In this paper, the relationship between loss in the process of magnetization and microstructure of materials is analyzed. The features of eddy current loss and hysteresis loss were found from the pulsed eddy current signals, and the yield strength evaluation model was established by feature fitting. The experimental results show that the model has high evaluation accuracy.

Temperature-dependent hysteresis model for soft magnetic materials

PurposeTo understand the behavior of the magnetization processes in ferromagnetic materials in function of temperature, a temperature-dependent hysteresis model is necessary. This study aims to investigate how temperature can be accounted for in the energy-based hysteresis model, via an appropriate parameter identification and interpolation procedure.Design/methodology/approachThe hysteresis model used for simulating the material response is energy-consistent and relies on thermodynamic principles. The material parameters have been identified by unidirectional alternating measurements, and the model has been tested for both simple and complex excitation waveforms. Measurements and simulations have been performed on a soft ferrite toroidal sample characterized in a wide temperature range.FindingsThe analysis shows that the model is able to represent accurately arbitrary excitation waveforms in function of temperature. The identification method used to determine the model parameters has proven its robustness: starting from simple excitation waveforms, the complex ones can be simulated precisely.Research limitations/implicationsAs parameters vary depending on temperature, a new parameter variation law in function of temperature has been proposed.Practical implicationsA complete static hysteresis model able to take the temperature into account is now available. The identification is quite simple and requires very few measurements at different temperatures.Originality/valueThe results suggest that it is possible to predict magnetization curves within the measured range, starting from a reduced set of measured data.

Novel method for the accurate determination of magnetocrystalline energy from Barkhausen noise in ferromagnetic materials

A new method is presented for the estimation of the angular dependence of the magnetocrystalline energy from Barkhausen noise in API 5L steels in the branch from saturation to remanence. The magnetocrystalline energy was predicted from X-ray texture measurements and compared with the estimations produced from Barkhausen noise measurements in circular samples of six steels with different microstructures, crystallographic textures, and measuring planes. The angular dependences of the magnetocrystalline energy obtained from Barkhausen noise were in good agreement with the predictions made from X-ray texture measurements for all the studied steel samples and measuring planes. The results of this study corroborate that Barkhausen noise measurements based on the proposed method have the ability of accurately determining the magnetocrystalline energy in low-carbon steels and confirm that the strong correlation between the magnetocrystalline energy and the angular dependence of the Barkhausen noise signal is mainly due the role that crystallographic texture plays in the magnetization process of ferromagnetic materials in the branch from saturation to remanence.

Rayleigh Region in Amorphous and Nanocrystaline FINEMET Alloy

Magnetization processes in ferromagnetic materials can be described in four ways, reversible and irreversible domain wall (DW) motion, rotation of the vector of magnetic polarization, and paraprocess in high magnetic elds. The process of reversible DW motion is characteristic for the range of small exciting magnetic elds the Rayleigh region (RR). The dependence of magnetic polarization J in this region, called also the region of initial susceptibility (permeability), on the magnetic eld strength H can be expressed by the following equation

Theoretical Model of Temperature Dependence of Hysteresis Based on Mean Field Theory

The magnetization processes in ferromagnetic materials are dependent on temperature. In order to understand thoroughly the behavior of magnetization processes in ferromagnetic materials at different temperatures, a temperature dependent hysteresis model is necessary. In the present study, a physical model based on Jiles-Atherton (JA) theory was developed to study the effects of temperature on magnetic hysteresis. This was achieved through the introduction of temperature dependent hysteresis parameters of the existing model. The material dependent parameters such as Curie temperature and critical exponent have also been added as additional variables to the existing model. The temperature dependent extension of the JA model was validated against measurements made on cation substituted cobalt ferrite material and the results show good agreement between theory and experiment.

Modeling the Temperature Dependence of Hysteresis Based on Jiles–Atherton Theory

A temperature-dependent model is necessary in order to understand the behavior of magnetization processes in ferromagnetic materials at different temperatures. In the present study, a physical model based on Jiles-Atherton (JA) theory was developed to study the effects of temperature on magnetic hysteresis. The thermal effects were incorporated through temperature-dependent hysteresis parameters of the existing model, adding critical exponent and Curie temperature as additional parameters. The temperature-dependent JA model was validated against measurements made on substituted cobalt ferrite material, and the results were in good agreement.

Susceptibility Spectroscopy in FeNiSiB Microwires

Amorphous magnetic microwires are novel materials, which are characterized by unusual soft magnetic properties, such as magnetic bistability and Giant MagnetoImpedance (GMI) effect [1]. The magnetic behavior of this microwire strongly depends on their composition, which is directly responsible of the sign and magnitude of magnetostriction constant, and also on the values and distribution of internal stresses induced during preparation [2]. The magnetic properties of amorphous microwires are usually described in terms of the core-shell model [3]. In accordance with the model, a microwire with positive magnetostriction consists of one large axial domain surrounded by the outer domains with radially oriented magnetization. Measurement of the amplitude dependence of the complex susceptibility is a useful method for studying dynamic magnetization processes in ferromagnetic materials because the magnetization processes can be resolved [4, 5]. We apply this method here to study the magnetization process in amorphous glass-coated FeNiSiB microwires with different Fe/Ni ratios.

B203 バルクハウゼン現象の可視化法に関する一考察

Ferromagnetic materials, i.e., iron steel and its composites, are widely used as the frame parts of various artificial products and constructions such as a building, bridge and so on. Because of its mechanical property, iron steel is most popular in use for the frame materials to maintain their mechanical strength. On the other side, nondestructive testing of iron steel is an extremely important way in order to keep their mechanical safeness.One of the deterministic differences between the ferromagnetic and non-magnetic materials is that all of the ferromagnetic materials when applying external magnetic field attracts major magnetic field; and also magnetization process of ferromagnetic materials always accompanies with the Barkhausen effects. Barkhausen effect is a phenomenon, which happens by movement of magnetic domain.Magnetic domain structure evaluation of most magnetic material is performed in the uniform magnetic field distribution. In this paper, we propose a designing strategy of the optimal exciting coil as the first step of a nondestructive testing method employing Barkhausen phenomenon. Further, we propose one of the visualizing methodologies of the Barkhausen phenomenon as the second step.

知的可視化情報処理による強磁性体認識

Ferromagnetic materials, i.e., iron steel and its composites, are widely used as the frame parts of various artificial products and constructions such as automobile, air plane, building, bridge and so on. Because of its mechanical property, iron steel is most popular in use for the frame materials to maintain their mechanical strength. On the other side, nondestructive testing of iron steel is an extremely important way in order to keep their mechanical safeness.One of the deterministic differences between the ferromagnetic and non-magnetic materials is that all of the ferromagnetic materials when applying external magnetic field attracts major magnetic field; and also magnetization process of ferromagnetic materials always accompanies with the Barkhausen effects.In the present paper, we propose a new nondestructive testing methodology for the ferromagnetic materials fully utilizing the Barkhausen effects along with smart visualized information processing.

Stress Effect on Magnetoacoustic Emission of Nickel.

Acoustic emission (AE) is stress pulses generated during dynamic processes in solids. AE is reflected by structural change of the material such as dislocation and crack growth and it is utilized as nondestructive evaluation technique for fracture or fatigue. On the other hand. AE is also observed during dynamic magnetization process of ferromagnetic materials. The phenomenon is called Magnetoacoustic Emission (MAE), and it is caused by abrupt and discontinuous displacement of magnetic domain walls pinned by inclusions, voids, dislocations, grain boundaries etc. Moreover, the characteristics of MAE change with the applied stress since the stress influences the structure of the magnetic domains and the pinning effects. This paper reports that the total event count of MAE for nickel decreases with the tensile stress and increases with compressive stress in the case when the stress is parallel to the magnetic field.

Analysis of a magnetization process based on a two sublattice model

A computer simulation program, based on a two sublattice model, is performed to analyze the magnetization process of ferromagnetic materials (like, for instance, RCo5 and R2Fe14B compounds). Without using the assumption of the existence of a small canting angle between the two sublattices, as has been used in the analysis of S. Rinaldi and L. Pareti [J. Appl. Phys. 50, 7719 (1979)], the magnetization curve as well as its derivative curves are studied for the two sublattice system with high competing single-ion anisotropies. In the present work, a peak in the low field range of the second curve of magnetization is reported and the magnetic process is correspondingly discussed in terms of both the exchange energy and the anisotropy.