Effect Of High Magnetic Field Research Articles

High Magnetic Field Effects on Cu-precipitation Behavior of Fe-1mass%Cu at 773 K

High Magnetic Field Effects on Cu-precipitation Behavior of Fe-1mass%Cu at 773 K

Mechanism of High Magnetic Field Effect on the D03-L12 Phase Transition in Fe-Ga Alloys

Mechanism of High Magnetic Field Effect on the D03-L12 Phase Transition in Fe-Ga Alloys

Effects of High Magnetic Fields on the Diffusion of Biologically Active Molecules

The diffusion of biologically active molecules is a ubiquitous process, controlling many mechanisms and the characteristic time scales for pivotal processes in living cells. Here, we show how a high static magnetic field (MF) affects the diffusion of paramagnetic and diamagnetic species including oxygen, hemoglobin, and drugs. We derive and solve the equation describing diffusion of such biologically active molecules in the presence of an MF as well as reveal the underlying mechanism of the MF’s effect on diffusion. We found that a high MF accelerates diffusion of diamagnetic species while slowing the diffusion of paramagnetic molecules in cell cytoplasm. When applied to oxygen and hemoglobin diffusion in red blood cells, our results suggest that an MF may significantly alter the gas exchange in an erythrocyte and cause swelling. Our prediction that the diffusion rate and characteristic time can be controlled by an MF opens new avenues for experimental studies foreseeing numerous biomedical applications.

Effect of High Static Magnetic Fields on Biological Activities and Iron Metabolism in MLO-Y4 Osteocyte-like Cells.

There are numerous studies that investigate the effects of static magnetic fields (SMFs) on osteoblasts and osteoclasts. However, although osteocytes are the most abundant cell type in bone tissue, there are few studies on the biological effects of osteocytes under magnetic fields. Iron is a necessary microelement that is involved in numerous life activities in cells. Studies have shown that high static magnetic fields (HiSMF) can regulate cellular iron metabolism. To illustrate the effect of HiSMF on activities of osteocytes, and whether iron is involved in this process, HiSMF of 16 tesla (T) was used, and the changes in cellular morphology, cytoskeleton, function-related protein expression, secretion of various cytokines, and iron metabolism in osteocytes under HiSMF were studied. In addition, the biological effects of HiSMF combined with iron preparation and iron chelator on osteocytes were also investigated. The results showed that HiSMF promoted cellular viability, decreased apoptosis, increased the fractal dimension of the cytoskeleton, altered the secretion of cytokines, and increased iron levels in osteocytes. Moreover, it was found that the biological effects of osteocytes under HiSMF are attenuated or enhanced by treatment with a certain concentration of iron. These data suggest that HiSMF-regulated cellular iron metabolism may be involved in altering the biological effects of osteocytes under HiSMF exposure.

Effects of High Magnetic Field on Partial Discharge and Flashover Behavior of Epoxy Resin

High-field magnets use epoxy resin as the insulation for superconducting coil terminals. Surface flashover on the interface between the gas and solid insulation will cause insulation failure. In this paper, effects of high magnetic field on surface partial discharge and surface flashover of the epoxy resin are investigated. Experimental results show that high magnetic field causes the decrease of relative permittivity and further changes the electric field distribution along the surface of epoxy resin. Surface partial discharge behavior is directed by both the decrease of surface electric field at the interface and the decrease of breakdown voltage of air gap in high magnetic field. Lorentz force begins to play a role during the extension of electron avalanche by changing the migration of charge carriers and weakening the equivalent effect of the normal electric field near the triple junction. Opposite trends are observed with the increase of magnetic flux density when the direction of Lorentz force is parallel or perpendicular to the surface of epoxy resin.

Influence of a High Static Magnetic Field on the Morphology of Primary Al3Fe Phase in Al-3%Fe Alloy

It had been done the experiments of the solidification on Al-Fe alloy under a high static magnetic field (10T). The effect of high magnetic field on the morphology of primary Al3Fe phase in Al-3%Fe alloy solidification structure has been investigated by analyzing the microstructures. The experimental results shew that the variation of the morphology of Al3Fe phase was obvious under a high static magnetic field, and them changed to particle-likes and short needles from needle-likes, and they were arranged in chains along the direction of magnetic field to form oriented layered structure. The critical nucleation work reduced and the nucleation rate increased under the applied field, and the magnetic interaction caused by the field can suppress the growth of needle-like Al3Fe phase, both of them resulted in the particle-likes and short needles grains of primary Al3Fe phase to nucleate and grow preferentially. Under the action of magnetic moment and the magnetic interaction force a high static magnetic field, the grains of Al3Fe rotated and then polymerized, and finally formed chain arrangements and layer structures.

Effects of high static magnetic field on the microstructure of Zn-Bi monotectic alloys during directional solidification process

Directional solidification of Zn-0.63 at% Bi monotectic alloys at different growth rates with and without a 5-T high static magnetic field (HSMF) was studied. Regardless of whether an HSMF was applied, the solid–liquid (S–L) interface changed in a consistent manner with increasing growth rate. The HSMF affected the S–L interface morphology and solidified microstructure by suppressing melt convection above the S–L interface. Two mechanisms led to the formation of strings of droplets. One was the Rayleigh instability of fibres caused by the bulk diffusion process as a result of the minimisation of the total interfacial energy of the system. The HSMF improved the stability of the fibre phase by reducing the interfacial energy, thereby helping to process material with a complete fibre-coupled growth structure, which has a greater specific surface area. The other was that constitutional instability at the S–L interface only existed when the growth rate was 3 µm/s under a 5-T HSMF. A revised stability-limit-diagram model was mapped to reveal solidification mechanism in monotectic systems. This work offers a new approach for processing functional monotectic alloy materials in the future.

Effect of high magnetic field assisted heat treatment on microstructure and properties of AlCoCrCuFeNi high-entropy alloy

High magnetic field assisted heat treatment process was used to regulate the microstructure and properties of AlCoCrCuFeNi high-entropy alloy. Results show that applying magnetic field can refine the FeCoCr-rich phase and suppress the large regional segregation of Cu-rich phase. The strength of the alloy increases greatly from 1482 MPa to 1795 MPa and the elongation also increases from 23% to 27%. The saturation magnetization is depressed after the magnetic field is applied. These variations are attributed to the decrease of Cu-rich phase segregation, grain refinement, and also the slightly decreased volume fraction of BCC phase upon applying high magnetic field.

Coupling effects of high magnetic field and annealing on the microstructure evolution and mechanical properties of additive manufactured Ti–6Al–4V

Additive manufacturing (AM) is playing a critical role in the areas of in-space intelligent manufacturing and on-orbital serving technologies. One of challenges is to reveal the composition-processing-microstructure-property relationship during post-treatment process, which would promote the AMed-product with excellent quality. In present work, the integration of heat and magnetic fields provides an approach to optimize microstructures and to enhance the mechanical properties of the selective laser melting (SLM) fabricated Ti–6Al–4V alloy. The conditions for post-treatment processes are set up to 400 °C for 30 min with 2 T, 4 T, 6 T, 8 T and 10 T, respectively. This coupling effects not only promote the phase transformation of α'→α+β, but also modify the width of the α'/α phases. The α'/α morphology after post-treatment becomes finer than the as-built ones, attributing to grain refinement strengthening. Moreover, the yield strength and the ductility of the annealed specimen in 8 T high magnetic field are 1092.1 MPa and 15.1% respectively, which could beat the classical reported SLM-fabricated ones and be comparable to the wrought ones. This work provides the connections between magnetic heating treatments and mechanical properties, paving a path to accelerate the development of space technology and exploration.

Variations in the effects caused by magnetic field on chlorophyll, nitrogen, calcium, and iron contents in species of vegetable plants

The rates of reduction in chlorophyll and nutrients such as nitrogen, calcium and iron with the distance or range of source of Magnetic Field (MF) had not been considered. In this work, patterns of damage or reduction caused by a magnetic field on two different species of vegetables were studied. The first group was planted in an environment without the influence of MF, while the second group was subjected to high MF under the 330 kV electric lines. The magnetometer was used to measure the MF intensities. The chlorophyll content of each vegetable sample was determined on the field with a portable chlorophyll meter. The dried harvested samples of two different vegetable species were analyzed using an Atomic Absorption Spectrophotometer (AAS) to assess the concentrations of nitrogen (N), calcium (Ca), and iron (Fe) in the samples. Results of elemental concentrations were subjected to statistical analysis to appraise the relationships between the measured variables as responses to high MF. It was observed that the effects of high MF are stronger on spinach vegetable than Lagos spinach. This suggested that the effects of MF on plants are not only MF intensity dependent, but also species-dependent.
 Keywords: Magnetic field; Exposure; Regression analysis; Power transmission; Chlorophyll; Iron

Low magnetic field promotes recombinant human BMP-2-induced bone formation and influences orientation of trabeculae and bone marrow-derived stromal cells

Effects of high magnetic fields [MFs, ≥ 1 T (T)] on osteoblastic differentiation and the orientation of cells or matrix proteins have been reported. However, the effect of low MFs (< 1 T) on the orientation of bone formation is not well known. This study was performed to verify the effects of low MFs on osteoblastic differentiation, bone formation, and orientation of both cells and newly formed bone. An apparatus was prepared with two magnets (190 mT) aligned in parallel to generate a parallel MF. In vitro, bone marrow-derived stromal cells of rats were used to assess the effects of low MFs on cell orientation, osteoblastic differentiation, and mineralization. A bone morphogenetic protein (BMP)-2-induced ectopic bone model was used to elucidate the effect of low MFs on microstructural indices, trabecula orientation, and the apatite c-axis orientation of newly formed bone. Low MFs resulted in an increased ratio of cells oriented perpendicular to the direction of the MF and promoted osteoblastic differentiation in vitro. Moreover, in vivo analysis demonstrated that low MFs promoted bone formation and changed the orientation of trabeculae and apatite crystal in a direction perpendicular to the MF. These changes led to an increase in the mechanical strength of rhBMP-2-induced bone. These results suggest that the application of low MFs has potential to facilitate the regeneration of bone with sufficient mechanical strength by controlling the orientation of newly formed bone.

Effects of high magnetic field on the growth and magnetic property of L10-FePtCu nanoparticles

Developing a novel strategy for promoting the disorder–order transition of FePt nanoparticles (NPs) is helpful to improve magnetic and electrocatalytic properties of the FePt NPs. In this research, high magnetic field (HMF) was introduced to wet-chemical synthesis of the L10-FePt NPs. The effects of HMF on the growth and magnetic property of wet-chemical synthesized L10-FePtCu NPs were studied. Cu atoms preferred to occupy the Fe-site in L10-FePt lattice at 6 T HMF, which facilitated this disorder–order transition and increased the ordering degree of L10-FePtCu NPs. When the magnetic dipolar interaction energy was much higher than the thermal energy, the HMF also enhanced the orientation attachment of L10-FePtCu NPs along 〈001〉 direction, which would lead to the increasing of growing rate and the aligning of NPs. The HMF increased the coercivity of L10-FePtCu NPs by increasing the grain size and the ordering degree. This work provides a promising method for controlling the disorder–order transition, the attachment growth, and the magnetic property of wet-chemical synthesized NPs.

Effect of High Static Magnetic Field (2 T-12 T) Exposure on the Mineral Element Content in Mice.

Relative stability of mineral elements in tissues is necessary for health. High static magnetic fields (HiSMFs) have been widely used in biomedical research and industry. However, the bioeffect of HiSMFs on animals is still unclear. In this study, we investigated the effects of HiSMF exposure on the levels of Mg, Fe, Zn, Ca, and Cu in the main organs of mice. The 8-week male C57BL/6 mice were treated by 2-4 T, 6-8 T, 10-12 T HiSMFs for 28 days. The mass fractions of Mg, Fe, Zn, Ca, and Cu in the liver, brain, kidney, and heart in mice were respectively measured by atomic absorption spectroscopy, and used to evaluate mineral element content in tissues. The 2-4 T HiSMF exposure has increased the Mg, Fe, and Ca content in the kidney, as well as the Zn content in the brain. The 6-8 T HiSMF exposure has increased the Zn level in the liver; Mg, Fe, and Ca levels in the kidney; and Fe level in the heart, while the Zn in the kidney, and Zn and Ca in the heart was decreased by 6-8 T HiSMF exposure. For the 10-12 T HiSMF exposure, the Mg in the kidney, the Fe in the liver and kidney, and Cu in the brain have been increased significantly. However, the Zn in the kidney and the Ca in the brain and the heart were reduced by 10-12 T HiSMF exposure. The HiSMF exposure for 28 days can alter the Mg, Fe, Zn, Ca, and Cu content in mice, and change with the differentmagnetic flux density of HiSMFs (2-4 T, 6-8 T, 10-12 T), elements, and organ types.

Effects of high magnetic field annealing on FePt nanoparticles with shape-anisotropy and element-distribution-anisotropy.

The concave-cube FePt nanoparticles (NPs) with shape-anisotropy and element-distribution-anisotropy were annealed under a high magnetic field (HMF). The NPs underwent spheroidization and phase transformation during the annealing process. The HMF hardly affected the spheroidizing process of NPs, but obviously facilitated the disorder-order transition of the L10-phase. The L10-phase content, ordering degree, and the coercivity of annealed NPs increased with enhancing the HMF strength. Those results indicated that the nucleation of the L10-phase and ordering diffusion of Fe/Pt atoms were promoted by the HMF.

Scale-invariant magnetic anisotropy in RuCl3 at high magnetic fields

In RuCl$_3$, inelastic neutron scattering and Raman spectroscopy reveal a continuum of non-spin-wave excitations that persists to high temperature, suggesting the presence of a spin liquid state on a honeycomb lattice. In the context of the Kitaev model, magnetic fields introduce finite interactions between the elementary excitations, and thus the effects of high magnetic fields - comparable to the spin exchange energy scale - must be explored. Here we report measurements of the magnetotropic coefficient - the second derivative of the free energy with respect to magnetic field orientation - over a wide range of magnetic fields and temperatures. We find that magnetic field and temperature compete to determine the magnetic response in a way that is independent of the large intrinsic exchange interaction energy. This emergent scale-invariant magnetic anisotropy provides evidence for a high degree of exchange frustration that favors the formation of a spin liquid state in RuCl$_3$.

Effect of high magnetic field on the phase transition in Fe-24%Ga and Fe-27%Ga during isothermal annealing

The effect of a high magnetic field (25 T) on the D03 to L12 phase transformation in two Fe-Ga alloys with 24 and 27 at.% Ga during isothermal annealing at 475 °C is investigated using neutron diffraction and magnetization measurements techniques. It is proved that annealing in the magnetic field increases the amount of fcc – derived L12 phase in both samples. This effect is stronger in the Fe-27%Ga alloy as compared with the Fe-24%Ga alloy. The reasons for enhancing the D03 to L12 phase transition in the magnetic field are discussed. We suggest that the most significant increase in the transformation rate is related to a decrease in the energy barrier between the phases involved in the transformation process.

High Magnetic Field Effects on the Solid-liquid Reaction of Fe–Ga System

High Magnetic Field Effects on the Solid-liquid Reaction of Fe–Ga System

Effect of high magnetic field on the recovery of tempered martensite

Influence of a 12 T high magnetic field on the recovery of tempered martensite in the chromium-containing steel was investigated. The results showed that a high magnetic field caused the percentage of low angle boundaries θ between 5° ~ 8° to increase by about 8%, while correspondingly decreased the percentage of high angle boundaries (>15°) by 9%. With the application of the magnetic field, the strain energy increased due to the higher density of free dislocations in the martensite, which leads to the retardation of recovery and little change in its lath shape due to the inhibition of the transition from low to high angle boundaries to maintain lower energy in the matrix.

Effect of high magnetic field on the microstructure evolution and mechanical properties of M50 bearing steel during tempering

The effect of high magnetic field (12 T) on the microstructure evolution and mechanical properties during tempering of M50 bearing steel have been investigated for evaluating the application prospect of magnetic field in steels. Microstructural observation shows that the high magnetic field can obviously accelerate the decomposition of retained austenite (RA) during the moderate tempering (at 300 or 380 °C), which could be ascribed to the increased dislocation in RA by the magnetic field-induced deformation of martensite. Meanwhile, the cementite precipitation is also increased by the applied high magnetic field because of the higher nucleation rate. Moreover, at higher tempering temperature of 530 °C, the Fe content in the precipitated carbides increases after applying high magnetic field, which is related to the different magnetization of carbides caused by various element content. Characterization of mechanical properties indicates that the tempered martensite embrittlement is significantly intensified during tempering at 380 °C, which is resulted from the accelerated RA decomposition and improved cementite precipitation under high magnetic field. When tempered at 530 °C in high magnetic field, the dislocation recovery is retarded and then the Vickers hardness and ultimate tensile strength (UTS) are thus improved by dislocation strengthening. This finding suggests the potential of high magnetic field (12 T) in optimizing the properties of M50 bearing steel during tempering (530 °C).

Thermally activated transformations in alloys with different type of magnetic ordering under high magnetic field

Abstract The paper presents new investigations of high magnetic field (HMF) effects on phase and structural transformations as well as historical development of the problem. The regularities of structure evolution under simultaneous action of heat treatment and high magnetic field have been studied on different alloys. It was shown, that magnetic field can affect thermodynamics and kinetics of transformation, which results in changes in the phase composition, crystallographic texture, rate of transformation, morphology of precipitating particles, and other effects. The observed phenomena strongly depend on magnetic properties of phases involved into transformation such as magnetic moment, magnetic susceptibility, magneto-crystalline anisotropy, magnetostriction. The review comprises the main results of modern researches into the influence of magnetic field of tens Tesla on the phase and structural transformations in materials with different type of magnetic ordering. Further research directions of HMF effect on the thermally activated transformations are proposed.