Application of a Dy3Co0.6Cu0.4Hx Addition for Controlling the Microstructure and Magnetic Properties of Sintered Nd-Fe-B Magnets

Skotnicová, Kateřina; Prokofev, Pavel A.; Kolchugina, N. B.; Бурханов, Г. С.; Lukin, A. A.; Koshkid’ko, Yu. S.; Čegan, Tomáš; Drulis, H.; Romanova, Tatyana; Dormidontov, N. A.

doi:10.3390/ma12244235

Cited by 5 publications

(3 citation statements)

References 27 publications

(32 reference statements)

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“…2). Cobalt cannot be observed in the alloy structure by SEM since, as it was shown in [12,13], the hydrogenolysis of the R3Co compounds (with R = Tb, Dy) leads to their decomposition with the formation of fine Co and Cu particles. The other components will improve the grain boundary structure via enhanced wettability between the Nd2Fe14B-based grains and the Nd-rich phase and decreasing exchange coupling between Nd2Fe14B-based grains [14,15].…”

Section: Study Of the Structure And Phase Composition Of Pr3(co06cu04)hxmentioning

confidence: 99%

Sintered permanent magnets prepared from hydrogenated (Nd-Fe-b strip-cast alloy + pr3(Co,cu) compound) mixture

Prokofev

Kolchugina

Skotnicová

et al. 2020

METAL 2020 Conference Proeedings

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The application of powder blending procedure shows promise in manufacturing Nd-Fe-B magnets; in this case, hydrides, oxides, intermetallic compounds, etc. are used as one of the mixture components. The application of these additions allows one to increase the hysteretic characteristics of Nd-Fe-B magnets at the expense of realized grain-boundary diffusion and grain-boundary structuring processes since these characteristics of the magnets are highly sensitive to their microstructure, composition of phases, and distribution of alloy components as well. This study is focused on the possibility of using the Pr3Co0.6Cu0.4Hx composition as the addition to the powder mixture for manufacturing Nd-Fe-B magnets and on the processes occurred during hydrogen treatment of the addition. The base alloy having the composition Nd-24.0, Pr-6.5, Dy-0.5, B-1.0, Al-0.2, Fe-balance was prepared by strip-casting and subjected to hydrogen decrepitation at 270 °C for 1 h. The Pr3Co0.6Cu0.4 alloy was prepared by arc melting in an argon atmosphere and subjected to homogenizing annealing at 600 °C for 90 h and subsequent hydrogenation under the conditions used for the strip-cast alloy. The phase composition of Pr3Co0.6Cu0.4Hx was studied by X-ray diffraction analysis, DTA, scanning electron microscopy, and electron microprobe analysis. The Pr3Co0.6Cu0.4Hx composition was shown to undergo the hydrogenolysis with the formation of PrHx hydride (or hydrogen solid solution in Pr), Co+Cu fine mixture, and PrCu compound. The behavior of the additions in manufacturing sintered permanent magnets is analyzed from the viewpoint of the grain-boundary structuring effect of the addition. The sintered magnet prepared from the hydrogenated mixture Nd-Fe-B strip-cast alloy + Pr3(Co,Cu) compound exhibits the following hysteretic parameters: Br = 1.35 T, jHc = 1008 kA/m, and (BH)max = 349 kJ/m 3 .

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Section: Study Of the Structure And Phase Composition Of Pr3(co06cu04)hxmentioning

confidence: 99%

Sintered permanent magnets prepared from hydrogenated (Nd-Fe-b strip-cast alloy + pr3(Co,cu) compound) mixture

Prokofev

Kolchugina

Skotnicová

et al. 2020

METAL 2020 Conference Proeedings

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“…Another fabrication method is to use powder-blend or dual alloy techniques, which involve typically a HRE-free Nd-Fe-B alloy mixed with HRE-rich powders (HRE hydrides, oxides, sulfide, and fluorides, [43][44][45][46][47][48] or intermetallics [23,49,50] ). Contrary to GBDP, the core-shell microstructure formed during sintering is homogeneously distributed at the magnet scale.…”

Section: Introductionmentioning

confidence: 99%

Toward the Improvement of the Short‐Loop Recycling of Dy‐Rich Nd–Fe–B Permanent Magnets: Experimental and Numerical Approaches

Bacchetta,

Luca,

Rado

et al. 2024

Adv Eng Mater

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The method of short‐loop recycling of Nd‐Fe‐B magnets is implemented, with End of Life (EoL) magnets used as a source of Heavy Rare Earths (HRE). Partially recycled magnets are fabricated by co‐sintering of HRE‐free powders obtained from strip casted alloys, blended with HRE‐rich powders obtained from EoL magnets. The impact of several process parameters (blending ratio, sintering cycle and HRE‐rich recycled particle sizes) on the microstructure and magnetic properties are discussed. A coercivity gain up to 160 kA m‐1 per wt. % of Dy with respect to the HRE‐free magnets is reported, even though impurities are incorporated. Microstructural characterizations show a heterogeneous Dy localization in core‐shell/anti‐core‐shell structures, and thus a non‐optimal use of HRE. The experimental results are compared with finite elements simulations performed using existing data of bulk Dy diffusion coefficients. The simulation model consists of a network of square grains separated by a liquid phase, whose fraction is based on the ternary Nd‐Fe‐B phase diagram. Results show similarities with the observed microstructures, and point to the interest of reducing the Dy‐rich particle size with respect to the main powder. This study provides new insights into the Dy transport mechanisms at stake in an efficient short‐loop recycling of HRE.This article is protected by copyright. All rights reserved.

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“…Further heat treatment at the temperature of 600-700 • C with slow cooling was needed to recover the transformation behaviour, which is crucial for the shape memory effect [7]. The magnetic materials were investigated by Skotnicova et al [8]. This paper focused on the coercivity enhancement of Nd-Fe-B magnets by optimizing the microstructure by the addition of a Dy 3 Co 0.6 Cu 0.4 H x alloy during mechanical activation.…”

mentioning

confidence: 99%

Advanced Powder Metallurgy Technologies

Novák

2020

Materials

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Powder metallurgy is a group of advanced processes for the synthesis, processing, and shaping of various kinds of materials. Initially inspired by ceramics processing, the methodology comprising of the production of a powder and its transformation to a compact solid product has attracted great attention since the end of World War II. At present, there are many technologies for powder production (e.g., gas atomization of the melt, chemical reduction, milling, and mechanical alloying) and its consolidation (e.g., pressing and sintering, hot isostatic pressing, and spark plasma sintering). The most promising ones can achieve an ultra-fine or nano-grained structure of the powder, and preserve it during consolidation. Among these methods, mechanical alloying and spark plasma sintering play a key role. This Special Issue gives special focus to the advancement of mechanical alloying, spark plasma sintering and self-propagating high-temperature synthesis methods, as well as to the role of these processes in the development of new materials.

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Application of a Dy3Co0.6Cu0.4Hx Addition for Controlling the Microstructure and Magnetic Properties of Sintered Nd-Fe-B Magnets

Cited by 5 publications

References 27 publications

Sintered permanent magnets prepared from hydrogenated (Nd-Fe-b strip-cast alloy + pr3(Co,cu) compound) mixture

Sintered permanent magnets prepared from hydrogenated (Nd-Fe-b strip-cast alloy + pr3(Co,cu) compound) mixture

Toward the Improvement of the Short‐Loop Recycling of Dy‐Rich Nd–Fe–B Permanent Magnets: Experimental and Numerical Approaches

Advanced Powder Metallurgy Technologies

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