Upscaling the 2‐Powder Method for the Manufacturing of Heavy Rare‐Earth‐Lean Sintered didymium‐Based Magnets

Opelt, Konrad; Ahmad, Tayyab; Diehl, Oliver; Schönfeldt, Mario; Brouwer, Eva; Vogel, Inga; Rossa, Jürgen D.; Gaßmann, J.; Ener, Semih; Gutfleisch, Oliver

doi:10.1002/adem.202100459

Cited by 13 publications

(11 citation statements)

References 43 publications

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“…Material parameters of each phase for micromagnetic simulations. α-Fe is the cubic stru ture, and K1 is a typical anisotropy constant of the soft-magnetic phase [15]. In several previous works, experimental studies were reported on the correlation be tween the composition of the GB phases and its magnetic behavior [3,39,40].…”

Section: Resultsmentioning

confidence: 99%

“…The addition of HRE elements during GBDP can repair these surface problems. The compositional design can also be performed by blending precursor powders with the different grain sizes and chemical compositions of Dy alloy powders, resulting in homogeneous HRE distribution [ 15 ]. Another available method to design the microstructures in permanent magnets is achieved by growing the materials layer by layer using the vacuum sputtering system [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

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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“…High-resolution TEM (HR-TEM) and diffraction patterns acquisitions were performed to detect the crystal structure of metastable phase (Figure 8). The diffractogram on a larger grain of the metastable phase can be assigned to [1][2][3][4][5][6][7][8][9][10][11][12] zone axis of the Nd 2 Fe 17 structure (No. 166; R-3m), which is consistent with the XRD data.…”

Section: Magnetic Hardening Of the Nd 16 Fe Bal-x-y-z Co X Mo Y Cu Z ...mentioning

confidence: 99%

“…[ 1–3 ] Most Nd‐Fe‐B magnets are sintered, with the grain size of the hard‐magnetic Nd 2 Fe 14 B phase being in the range of 2–10 µm. [ 1,4–6 ] There are some alternative process routes, for example, the hot deformation can produce textured Nd‐Fe‐B magnets with grain sizes in the sub‐micrometer range. [ 7,8 ] But irrespective of the way the magnets are made, the Nd 2 Fe 14 B grains are separated by a few‐nanometer‐thick Nd‐rich grain‐boundary layer, which reduces the presence of defects on the surfaces of the hard magnetic grains, decouples these grains, and helps prevent the nucleation of reverse magnetic domains in a demagnetizing field, which then leads to a high coercivity.…”

Section: Introductionmentioning

confidence: 99%

A Novel Magnetic Hardening Mechanism for Nd‐Fe‐B Permanent Magnets Based on Solid‐State Phase Transformation

Schäfer

Skokov

Maccari

et al. 2022

Adv Funct Materials

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Permanent magnets based on neodymium‐iron‐boron (Nd‐Fe‐B) alloys provide the highest performance and energy density, finding usage in many high‐tech applications. Their magnetic performance relies on the intrinsic properties of the hard‐magnetic Nd2Fe14B phase combined with control over the microstructure during production. In this study, a novel magnetic hardening mechanism is described in such materials based on a solid‐state phase transformation. Using modified Nd‐Fe‐B alloys of the type Nd16Febal‐x‐y‐zCoxMoyCuzB7 for the first time it is revealed how the microstructural transformation from the metastable Nd2Fe17Bx phase to the hard‐magnetic Nd2Fe14B phase can be thermally controlled, leading to an astonishing increase in coercivity from ≈200 kAm−1 to almost 700 kAm−1. Furthermore, after thermally treating a quenched sample of Nd16Fe56Co20Mo2Cu2B7, the presence of Mo leads to the formation of fine FeMo2B2 precipitates, in the range from micrometers down to a few nanometers. These precipitates are responsible for the refinement of the Nd2Fe14B grains and so for the high coercivity. This mechanism can be incorporated into existing manufacturing processes and can prove to be applicable to novel fabrication routes for Nd‐Fe‐B magnets, such as additive manufacturing.

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“…The microstructure must allow reaching the highest possible coercivity and remanent induction and a magnetization loop close to a rectangular one. The achievement of each of these objectives is facilitated by the existence of a granular microstructure [ 2 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ].…”

Section: Introductionmentioning

confidence: 99%

Structure and Magnetic Properties of Intermetallic Rare-Earth-Transition-Metal Compounds: A Review

Bessaïs

2021

Materials

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This review discusses the properties of candidate compounds for semi-hard and hard magnetic applications. Their general formula is R1−sT5+2s with R = rare earth, T = transition metal and 0≤s≤0.5 and among them, the focus will be on the ThMn12- and Th2Zn17-type structures. Not only will the influence of the structure on the magnetic properties be shown, but also the influence of various R and T elements on the intrinsic magnetic properties will be discussed (R = Y, Pr, Nd, Sm, Gd, … and T = Fe, Co, Si, Al, Ga, Mo, Zr, Cr, Ti, V, …). The influence of the microstructure on the extrinsic magnetic properties of these R–T based intermetallic nanomaterials, prepared by high energy ball milling followed by short annealing, will be also be shown. In addition, the electronic structure studied by DFT will be presented and compared to the results of experimental magnetic measurements as well as the hyperfine parameter determined by Mössbauer spectrometry.

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Upscaling the 2‐Powder Method for the Manufacturing of Heavy Rare‐Earth‐Lean Sintered didymium‐Based Magnets

Abstract: The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adem.202100459.

Cited by 13 publications

References 43 publications

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

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

A Novel Magnetic Hardening Mechanism for Nd‐Fe‐B Permanent Magnets Based on Solid‐State Phase Transformation

Structure and Magnetic Properties of Intermetallic Rare-Earth-Transition-Metal Compounds: A Review

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