Microstructure and magnetic properties of grain boundary modified recycled Nd-Fe-B sintered magnets

JOURNAL OF ALLOYS AND COMPOUNDS

卷:694

Article

Sepehri-Amin, H.¹  Ohkubo, T.¹  Zakotnik, M.²  Prosperi, D.²  Afiuny, P.²  Tudor, C. O.²  Hono, K.¹ 

[1] Natl Inst Mat Sci, Elements Strategy Initiat Ctr Magnet Mat, 1-2-1 Sengen, Tsukuba, Ibaraki 3050047, Japan

[2] Urban Min Technol Co, Wilmington, DE USA

关键词: Nd-Fe-B sintered magnets;    Recycling;    Coercivity;    Grain boundary;    Microstructure;   

DOI  :  10.1016/j.jallcom.2016.09.305

来源: Elsevier

【 摘 要 】

Full-density recycled Nd-Fe-B sintered magnets were produced from collected waste Nd-Fe-B magnets with the coercivity, mu H-0(C), of 1.30 T and remanence, mu M-0(r), of 1.37 T. A small fraction of Nd6Dy21Co19Cu2.5Fe powder (Grain Boundary Modified (GBM (TM)) powder) was blended to the powders obtained from the Nd-Fe-B waste magnets. The addition of 5.0 wt% GBM (TM) powder resulted in mu H-0(C) = 2.36 T with, mu M-0(r) = 1.29 T in recycled magnets. The temperature coefficient of intrinsic coercivity, beta, in the recycled magnet was measured to be -0.47%/degrees C. Microstructure studies showed that the addition of the GBM (TM) powder increases the volume fraction of a metallic Nd-rich phase in the recycled magnets. 3D tomography revealed a good interconnection of Nd-rich phases through the grain boundaries of the recycled magnet. Microstructure studies suggested that obtained high coercivity in the recycled magnet with 5.0 wt% addition of GBM (TM) is due to the formation of distinct grain boundary phase combined with the formation of Dy-rich shell in the Nd2Fe14B grains with similar to 0.8 at. % Dy. (C) 2016 Elsevier B.V. All rights reserved.

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