Limitations in the Grain Boundary Processing of the Recycled HDDR Nd-Fe-B System

Autor: Kristina Žužek Rožman, Franci Pušavec, Awais Ikram, Muhammad Awais, Allan Walton, Spomenka Kobe, Richard Sheridan
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Materials science
Annealing (metallurgy)
Spark plasma sintering
redki zemeljski trajni magneti
02 engineering and technology
recycling
01 natural sciences
lcsh:Technology
Article
HDDR Nd2Fe14B
recikliranje
0103 physical sciences
HDDR Nd$_2$Fe$_{14}$B
Grain boundary diffusion coefficient
General Materials Science
visoka magnetna koercivnost
lcsh:Microscopy
Eutectic system
lcsh:QC120-168.85
010302 applied physics
sintranje s plazmo
lcsh:QH201-278.5
lcsh:T
Metallurgy
Coercivity
021001 nanoscience & nanotechnology
Nanocrystalline material
high coercivity
grain boundary diffusion processing (GBDP)
postopek difuzije meje zrn (GBDP)
rare earth permanent magnets
lcsh:TA1-2040
Magnet
udc:537.6(045)
Grain boundary
lcsh:Descriptive and experimental mechanics
lcsh:Electrical engineering. Electronics. Nuclear engineering
0210 nano-technology
lcsh:Engineering (General). Civil engineering (General)
lcsh:TK1-9971
spark plasma sintering
Zdroj: Materials
Volume 13
Issue 16
Materials, vol. 13, no. 16, 3528, 2020.
Materials, Vol 13, Iss 3528, p 3528 (2020)
ISSN: 1996-1944
DOI: 10.3390/ma13163528
Popis: Fully dense spark plasma sintered recycled and fresh HDDR Nd-Fe-B nanocrystalline bulk magnets were processed by surface grain boundary diffusion (GBD) treatment to further augment the coercivity and investigate the underlying diffusion mechanism. The fully dense SPS processed HDDR based magnets were placed in a crucible with varying the eutectic alloys Pr68Cu32 and Dy70Cu30 at 2&ndash
20 wt.% as direct diffusion source above the ternary transition temperature for GBD processing followed by secondary annealing. The changes in mass gain was analyzed and weighted against the magnetic properties. For the recycled magnet, the coercivity (HCi) values obtained after optimal GBDP yielded ~60% higher than the starting recycled HDDR powder and 17.5% higher than the SPS-ed processed magnets. The fresh MF-15P HDDR Nd-Fe-B based magnets gained 25&ndash
36% higher coercivities with Pr-Cu GBDP. The FEG-SEM investigation provided insight on the diffusion depth and EDXS analysis indicated the changes in matrix and intergranular phase composition within the diffusion zone. The mechanism of surface to grain boundary diffusion and the limitations to thorough grain boundary diffusion in the HDDR Nd-Fe-B based bulk magnets were detailed in this study.
Databáze: OpenAIRE
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