Effect of particle size on grain growth of Nd-Fe-B powders produced by gas atomization

Sarriegui, G.; Martín, José Manuel Perlado; Burgos, N.; Ipatov, M.; Zhukov, A.; González, J.

doi:10.1016/j.matchar.2022.111824

Cited by 7 publications

(2 citation statements)

References 44 publications

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“…In a most recent work [23] amorphous powders of Fe 78 Si 9 B 13 and solid powders of NH 4 NO 3 were milled for extended periods of up to 80 h. Although the formation of the α -Fe 16 N 2 phase was observed, the volume fraction was low, resulting in magnetization of very low saturation at 72.5 emu/g and a moderate coercivity of 541 Oe. A typical and affordable method for the mass production of micrometric metal and alloy powders is the gas atomization technique [28][29][30][31]. The idea is to transfer the kinetic energy from a high-velocity gas jet expanded through a nozzle, to a jet of liquid metal, resulting in fragmentation and breaking down into metal droplets.…”

Section: Introductionmentioning

confidence: 99%

Innovative Method for the Mass Preparation of α″-Fe16N2 Powders via Gas Atomization

Grigoras,

Lostun,

Porcescu

et al. 2023

Crystals

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The iron nitride materials, especially α″-Fe16N2, are considered one of the most promising candidates for future rare-earth-free magnets. However, the mass production of α″-Fe16N2 powders as a raw material for permanent magnets is still challenging. In this work, starting from iron lumps as a raw material, we have managed to prepare the α″-Fe16N2 powders via the gas atomization method, followed by subsequent nitriding in an ammonia–hydrogen gas mixture stream. The particle size was controlled by changing the gas atomization preparation conditions. X-ray diffractograms (XRD) analyses show that the prepared powders are composed of α″-Fe16N2 and α-Fe phases. The α″-Fe16N2 volume ratio increases with decreasing powder size and increasing nitriding time, reaching a maximum of 57% α″-Fe16N2 phase in powders with size below 32 ± 3 μm after 96 h nitridation. The saturation magnetization reaches the value of 237 emu/g and a reasonable coercivity value of 884 Oe. Compared to the saturation magnetization values of α-Fe powders, the α″-Fe16N2 powders prepared through our proposed approach show an increase of up to 10% in saturation and demonstrate the possibility of mass production of α″-Fe16N2 powders as precursors of permanent magnets without rare earths.

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Section: Introductionmentioning

confidence: 99%

Innovative Method for the Mass Preparation of α″-Fe16N2 Powders via Gas Atomization

Grigoras,

Lostun,

Porcescu

et al. 2023

Crystals

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show abstract

“…However, in real sintered magnets, coercivity is far below the limit that could be expected from a certain fraction of the anisotropy field ( H A ) of the τ1 phase [ 3 ]. In addition, the poor temperature stability of Nd–Fe–B-based magnets leads to remanence and coercivity decreasing rapidly when the operating temperature rises over 150 °C [ 4 , 5 ]. To compensate for the loss and satisfy the application needs, Nd is usually partially substituted with heavy rare-earth (HRE) elements such as Dy or Tb, resulting in a higher anisotropy field H A of the τ1 phase [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

Magnetic-Property Assessment on Dy–Nd–Fe–B Permanent Magnet by Thermodynamic Calculation and Micromagnetic Simulation

Dai

Wang

et al. 2022

Materials

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Heavy rare-earth (HRE) elements are important for the preparation of high-coercivity permanent magnets. A further understanding of the thermodynamic properties of HRE phases, and the magnetization reversal mechanism of magnets are still critical issues to obtain magnets that can achieve better performance. In this work, the Nd–Dy–Fe–B multicomponent system is investigated via the calculation of the phase diagram (CALPHAD) method and micromagnetic simulation. The phase composition of magnets with various ratios of Nd and Dy is assessed using critically optimized thermodynamic data. γ-Fe and Nd2Fe17 phases are suppressed when partial Nd is substituted with Dy (<9.3%), which, in turn, renders the formation of Nd2Fe14B phase favorable. The influence of the magnetic properties of grain boundaries (GBs) on magnetization reversal is detected by the micromagnetic simulations with the 3D polyhedral grains model. Coercivity was enhanced with both 3 nm nonmagnetic and the hard-magnetic GBs for the pinning effect besides the GBs. Moreover, the nucleation and propagation of reversed domains in core-shell grains are investigated, which suggests that the magnetic structure of grains can also influence the magnetization reversal of magnets. This study provides a theoretical route for a high-efficiency application of the Dy element, realizing a deterministic enhancement of the coercivity in Nd–Fe–B-based magnets.

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Comparative Analysis of Microstructural and Mechanical Attributes in Low-Pressure Cold-Spray Coatings: Impact of Varied Cu Feedstock Powders

Eftekhari,

Jahed

2024

J Therm Spray Tech

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Effect of particle size on grain growth of Nd-Fe-B powders produced by gas atomization

Cited by 7 publications

References 44 publications

Innovative Method for the Mass Preparation of α″-Fe16N2 Powders via Gas Atomization

Innovative Method for the Mass Preparation of α″-Fe16N2 Powders via Gas Atomization

Magnetic-Property Assessment on Dy–Nd–Fe–B Permanent Magnet by Thermodynamic Calculation and Micromagnetic Simulation

Comparative Analysis of Microstructural and Mechanical Attributes in Low-Pressure Cold-Spray Coatings: Impact of Varied Cu Feedstock Powders

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