Effect of Tb3Co0.6Cu0.4 addition on the microstructure and phase composition of low-REM Nd-Fe-B sintered magnet

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989100%3A27360%2F18%3A10241407" target="_blank" >RIV/61989100:27360/18:10241407 - isvavai.cz</a>

Result on the web

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DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Effect of Tb3Co0.6Cu0.4 addition on the microstructure and phase composition of low-REM Nd-Fe-B sintered magnet

Original language description

High-coercivity Nd-Fe-B magnets are demanded for clean energy applications, in particular, for hybrid and electric vehicles. The magnetic characteristics of sintered Nd-Fe-B magnets are highly sensitive to their microstructure and composition of phases. This paper is focused on the coercivity enhancement of the near-stoichiometric Nd2Fe14B-based magnet by optimizing microstructure, which included processes of grain boundary diffusion and grain boundary structuring via the application of hydrogenated Tb3Co0.6Cu0.4Hx composition added to the powder mixture. 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 technique and subjected to hydrogen decrepitation during heating to 270 oC in a hydrogen flow at a pressure of 0.1 MPa and subsequent 1 h dwell at this temperature. The Tb3Co0.6Cu0.4 alloy was prepared by arc melting of starting components in an argon atmosphere on a water-cooled copper bottom using a non-consumable tungsten electrode. The ingot was subjected to homogenizing annealing at 600 oC for 90 h and subsequent hydrogenation under the conditions used for the decrepitation of strip-cast alloy. Hydrogenated Tb3Co0.6Cu0.4Hx compound and hydrogen-decrepitated strip-cast alloy were mixed and subjected to mechanical activation. The microstructure, phase composition and distributions of REM, Co, Cu for the prepared magnets were investigated by SEM/EDX method. It was found that the total REM content in the main magnetic (Nd, Pr, Tb)2Fe14B phase was 30 wt.%. Intergranular Nd-rich phases differing by their Tb, Co, Cu contents were identified. Studies of the stability of structure-sensitive parameter, namely, the coercive force jHc of the sintered magnet prepared with 2 wt.% of Tb3Co0.6Cu0.4Hx addition to the low-temperature heat treatments show the increase in the coercive force up to 1480 kA/m. This phenomenon is not typical of sintered Nd-Fe-B magnets, which usually demonstrates the drop (or invariance) of the coercive force after low-temperature heat treatments at 350-450 oC.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

20501 - Materials engineering

Project

<a href="/en/project/LTARF18031" target="_blank" >LTARF18031: Development of physico-chemical and engineering foundations for the initiation of innovative resources-economy technology of high-power and high-coercivity (Nd,R)-Fe-B (R = Pr, Tb, Dy, Ho) low-REM permanent magnets</a><br>

Continuities

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

Publication year

2018

Confidentiality

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