New material for permanent magnets on a base of Nd and Fe (invited)

Sagawa, M.; Fujimura, S.; Togawa, Norio; Yamamoto, H.; Matsuura, Yutaka

doi:10.1063/1.333572

Cited by 2,732 publications

(710 citation statements)

References 5 publications

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“…Its particles were composed of nanocrystalline grains of the Nd 2 Fe 14 B phase, having a mean size of around 30 nm. The theoretical density of the Nd-Fe-B powder was 7.51 g/cm 3 .…”

Section: Methodsmentioning

confidence: 96%

“…It has also been reported that HE can be successfully applied to processes of consolidation of hard magnetic powders [2], however, powder metallurgy is still the most commonly used method of powder densification [3]. The undoubted advantage of HE is the very short time of the extrusion, and tri-axial state of stress, continuously acting at the billet during the entire process of hydrostatic extrusion.…”

Section: Introductionmentioning

confidence: 99%

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Consolidation of Nanocrystalline Nd-Fe-B Powder by Hydrostatic Extrusion at High Temperature

et al. 2017

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Hydrostatic extrusion is a modern method of shaping material microstructure and properties. Hydrostatic extrusion can also be successfully used for consolidation of hard magnetic powders. The effect of extrusion temperature, within the range of 700-800 • C, on the magnetic properties of the bulk, final product was studied. A commercial MQU-F42 powder, dedicated to hot pressing, was placed in copper capsules and initially cold compacted up to 60% of the theoretical density. Subsequently, the billet was heated in an oven to temperatures 700 and 800 • C, respectively and subjected to hydrostatic extrusion. The extruded product had a form of a copper rod, with the Nd-Fe-B core, having 96% of theoretical density (true strain 1.85 after extrusion at 800 • C). The extrusion process led to deterioration of the coercivity, for which coarsening of the Nd2Fe14B grains was blamed. In order to prove this hypothesis, the starting powder was annealed in a temperature range of 550-900 • C for various times. The crystallite size, measured after annealing by the X-ray diffraction method, showed that with extension of time and elevation of the temperature the crystallite size increases, however the dominating parameter is the temperature. Correlation of the crystallite size with temperature indicates that when the crystallites are larger than 80 nm the magnetic properties dramatically decrease. Additionally, after HE at 800 • C micrometric size Nd-rich phase appear in the microstructure. The Nd is squeezed from the grain boundary of the Nd2Fe14B phase leading to non-isolated grains, which also contributes to the deterioration of the coercivity.

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“…Its particles were composed of nanocrystalline grains of the Nd 2 Fe 14 B phase, having a mean size of around 30 nm. The theoretical density of the Nd-Fe-B powder was 7.51 g/cm 3 .…”

Section: Methodsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Consolidation of Nanocrystalline Nd-Fe-B Powder by Hydrostatic Extrusion at High Temperature

et al. 2017

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“…For higher force and energy density, neodymium permanent magnets are generally selected because of their outstanding magnetic properties [26]. From a microfabrication and ease of assembly perspective, the use of magnetic materials that can be directly deposited in a batch fabrication process might be appealing.…”

Section: Magnet Dimensions and Magnetizationmentioning

confidence: 99%

Optimization of the force and power consumption of a microfabricated magnetic actuator

Zárate

Tosolini

Petroni

et al. 2015

Sensors and Actuators A: Physical

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a b s t r a c tThe force (F) and the power consumption (P) of a magnetic actuator are modeled, measured and optimized in the context of developing micro-actuators for large arrays, such as in portable tactile displays for the visually impaired. We present a novel analytical approach complemented with finite element simulation (FEM) and experiment validation, showing that the optimization process can be performed considering a single figure of merit F/ √ P. The magnetic actuator is a disc-shaped permanent magnet displaced by planar microcoil. Numerous design parameters are evaluated, including the width and separation of the coil traces, the trace thickness, number of turns and the maximum and minimum radius of the coil. We obtained experimental values of F/ √ P ranging from 2 to 12 mN/ √ W using up to 2-layer coils of both microfabricated and commercial printed circuit board (PCB) technologies. This performance can be further improved by a factor of two by adopting a 6-layer technology. The method can be applied to a wide range of electromagnetic actuators.

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“…Sintered Nd-Fe-B permanent magnets have been widely used due to their excellent magnetic properties [1][2][3]. The increasing demand has resulted in the enormous production of Nd-Fe-B magnets.…”

Section: Introductionmentioning

confidence: 99%

Recycling of Sintered Nd-Fe-B Magnets Doped with PrNd Nanoparticles

Zhang¹,

Liu²,

Li³

et al. 2015

Journal of Magnetics

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The waste of sintered Nd-Fe-B magnets was recycled using the method of dopingPrNd nanoparticles. The effect of PrNd nanoparticle doping on the magnetic properties of the regenerated magnets has been studied. As the content of the PrNd nanoparticles increases, the coercivity increases monotonically, whereas both the remanence and the maximum energy products reach the maximum values for 4 wt% PrNd doping. Microstructural observation reveals that the appropriate addition of PrNd nanoparticles improves the magnetic properties and refines the grain. Domain investigation shows that the self-pinning effect of the rare earth (Re)-rich phase is enhanced by PrNd nano-particle doping. Compared to the magnet with 4 wt% PrNd alloy prepared using the dual-alloy method, the regenerated magnet doped with the same number of PrNd nanoparticles exhibits better magnetic properties and a more homogeneous microstructure. Therefore, it is concluded that PrNd nanoparticle doping is an efficient method for recycling the leftover scraps of Nd-Fe-B magnets.

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New material for permanent magnets on a base of Nd and Fe (invited)

Cited by 2,732 publications

References 5 publications

Consolidation of Nanocrystalline Nd-Fe-B Powder by Hydrostatic Extrusion at High Temperature

Consolidation of Nanocrystalline Nd-Fe-B Powder by Hydrostatic Extrusion at High Temperature

Optimization of the force and power consumption of a microfabricated magnetic actuator

Recycling of Sintered Nd-Fe-B Magnets Doped with PrNd Nanoparticles

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