Application of HoH2 hydride for improving the hysteretic properties of Pr-Fe-B magnets at low temperatures

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989100%3A27360%2F18%3A10241408" target="_blank" >RIV/61989100:27360/18:10241408 - isvavai.cz</a>

Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Application of HoH2 hydride for improving the hysteretic properties of Pr-Fe-B magnets at low temperatures

Popis výsledku v původním jazyce

Currently, processes named as grain boundary diffusion and grain boundary restructuring are widely used as approaches, which allow one to improve hysteretic properties of Nd-Fe-B-based magnets, namely, to enhance the coercivity and reduce the heavy rare-earth consumption of Nd-Fe-B sintered magnets simultaneously. Some progresses have been made in efforts to introduce heavy rare-earth metals (REMs) in the form of hydrides. In recent years, permanent magnets based on (Nd,Pr)2Fe14B compound are of interest for investigators owing to the possibility to use these magnets at low and cryogenic temperatures. In contrast to Nd2Fe14B compound (at 135 K, its easy-magnetization axis anisotropy changes to easy-axis cone anisotropy), the Pr2Fe14B compound does not undergo the spin-reorientation transition, and the natural increase in the hysteretic parameters with decreasing temperature can be adequately used. In the present study, we investigate the effect of HoH2 hydride addition on the hysteresis loop parameters of sintered Pr-Fe-Ti-Al-Cu-B magnets. The magnets were prepared by traditional powder metallurgy technology, and 3 wt. % HoH2 was added to the powder at the fine-milling stage. The magnets demonstrate the monotonic increase in all hysteretic parameters with decreasing temperature up to 4.2 K. The structure of the magnets was studied in detail by scanning electron microscopy (SEM/EDX), and the formation of so-called &quot;core-shell&quot; structure was demonstrated, which is assumed to favor the marked improvement of hysteretic properties of Pr-Fe-B-based magnets. The coercive force and maximum energy product at 4.2 K are Hc = 5420 kA/m and (BH)max = 352 kJ/m3, respectively. Domain structure of the magnets was studied perpendicular and parallel to the magnet texture using magnetic force microscopy. The data obtained indicate the well-formed magnetic texture. The average domain width is 1.2-1.8 um.

Název v anglickém jazyce

Application of HoH2 hydride for improving the hysteretic properties of Pr-Fe-B magnets at low temperatures

Popis výsledku anglicky

Currently, processes named as grain boundary diffusion and grain boundary restructuring are widely used as approaches, which allow one to improve hysteretic properties of Nd-Fe-B-based magnets, namely, to enhance the coercivity and reduce the heavy rare-earth consumption of Nd-Fe-B sintered magnets simultaneously. Some progresses have been made in efforts to introduce heavy rare-earth metals (REMs) in the form of hydrides. In recent years, permanent magnets based on (Nd,Pr)2Fe14B compound are of interest for investigators owing to the possibility to use these magnets at low and cryogenic temperatures. In contrast to Nd2Fe14B compound (at 135 K, its easy-magnetization axis anisotropy changes to easy-axis cone anisotropy), the Pr2Fe14B compound does not undergo the spin-reorientation transition, and the natural increase in the hysteretic parameters with decreasing temperature can be adequately used. In the present study, we investigate the effect of HoH2 hydride addition on the hysteresis loop parameters of sintered Pr-Fe-Ti-Al-Cu-B magnets. The magnets were prepared by traditional powder metallurgy technology, and 3 wt. % HoH2 was added to the powder at the fine-milling stage. The magnets demonstrate the monotonic increase in all hysteretic parameters with decreasing temperature up to 4.2 K. The structure of the magnets was studied in detail by scanning electron microscopy (SEM/EDX), and the formation of so-called &quot;core-shell&quot; structure was demonstrated, which is assumed to favor the marked improvement of hysteretic properties of Pr-Fe-B-based magnets. The coercive force and maximum energy product at 4.2 K are Hc = 5420 kA/m and (BH)max = 352 kJ/m3, respectively. Domain structure of the magnets was studied perpendicular and parallel to the magnet texture using magnetic force microscopy. The data obtained indicate the well-formed magnetic texture. The average domain width is 1.2-1.8 um.

Druh

O - Ostatní výsledky

CEP obor

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OECD FORD obor

20501 - Materials engineering

Projekt

<a href="/cs/project/LTARF18031" target="_blank" >LTARF18031: Vývoj fyzikálně-chemických a inženýrských základů pro iniciaci inovativní úsporné technologie výroby vysoce výkonných permanentních magnetů na bázi (Nd,R)-Fe-B (R = Pr, Tb, Dy, Ho) s nízkým obsahem kovů vzácných zemin</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2018

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů