OPTIMIZING THE MICROSTRUCTURE OF LOW-REM ND-FE-B SINTERED MAGNET USING DY3CO0.6CU0.4HX ADDITION

1,2 PROKOFEV Pavel A.
Co-authors:
1 KOLCHUGINA Natalia B. 1 BURKHANOV Gennadiy S. 2 LUKIN Alexander A. 1,3 KOSHKID’KO Yurii S. 4 SKOTNICOVA Katerina 4 CEGAN Tomas 3 DRULIS Henryk 3 ROMANOVA Tatyana 1 DORMIDONTOV Nikolay A.
Institutions:
1 Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences, Moscow, Russia, natalik014@yandex.ru, pav3387@yandex.ru
2 JSC SPETSMAGNIT”, Moscow, Russia, e-mail: lukinaalukin@rambler.ru
3 Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, Poland, EU HDrulis@int.pan.pl
4 VSB - Technical University of Ostrava, Ostrava, Czech Republic, EU, Katerina.Skotnicova@vsb.cz
Conference:
28th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, May 22nd - 24th 2019
Proceedings:
Proceedings 28th International Conference on Metallurgy and Materials
Pages:
1663-1670
ISBN:
978-80-87294-92-5
ISSN:
2694-9296
Published:
4th November 2019
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
44 views / 14 downloads
Abstract

In recent years, the application of various additions (hydrides, oxides, intermetallic compounds, etc.) to powder mixtures for manufacturing Nd-Fe-B magnets shows promise as the method that allows one to increase the hysteretic characteristics of the magnets at the expense of realized grain-boundary diffusion and grain-boundary structuring processes. The hysteretic 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 Dy3Co0.6Cu0.4Hx compound 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 °C in a hydrogen flow at a pressure of 0.1 MPa and subsequent 1 h holding at this temperature. Dy3Co0.6Cu0.4 alloy was prepared by arc melting in an argon atmosphere and subjected to homogenizing annealing at 600 °C for 90 h. The subsequent hydrogenation under the conditions used for the decrepitation of the strip-cast alloy. The phase composition of Dy3Co0.6Cu0.4 was studied by X-ray diffraction analysis, DTA and scanning electron microscopy, electron microprobe analysis. Additions of the hydrogenated compound to Nd-Fe-B-based sintered magnets allow us to manufacture magnets with Br = 1.34 T and jHc = 1120 kA/m. The microstructure, phase composition and distributions of REM, Co, Cu for the prepared magnets were investigated by SEM/EDX method. Stability of structure-sensitive parameter, namely, the coercive force jHc of the sintered magnet prepared with 2 wt% of Dy3Co0.6Cu0.4Hx addition was studied.

Keywords: Grain boundary diffusion, Nd-Fe-B magnets, hydrogenation, microstructure
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