TY - JOUR
T1 - Effect of annealing on magnetic properties of ultrafine jet-milled Nd-Fe-B powders
AU - Nakamura, Michihide
AU - Matsuura, Masashi
AU - Tezuka, Nobuki
AU - Sugimoto, Satoshi
AU - Une, Yasuhiro
AU - Kubo, Hirokazu
AU - Sagawa, Masato
N1 - Publisher Copyright:
©2014 The Japan Institute of Metals and Materials
PY - 2014
Y1 - 2014
N2 - This paper reports the effects of annealing on the magnetic properties of ultrafine Nd-Fe-B powders with an average particle size of 0.67 μm. The powder was fabricated from hydrogenation-disproportionation-desorption-recombination (HDDR)-treated Nd-Fe-B alloys by hydrogen decrepitation and helium jet milling. The coercivity of the ultrafine powders was slightly increased by annealing below 500°C, and was drastically increased by annealing above 600°C. These two stepwise increases in coercivity were attributed to hydrogen desorption and formation of a liquid Nd-rich phase. In addition, after annealing below 500°C, the coercivity (μ0Hc) of the ultrafine powder was higher than that of the conventional powder, which was prepared from a strip-cast Nd-Fe-B alloy power with a particle size of 1.12 μm, because of a decrease in particle size. In contrast, after annealing above 600°C, the μ0Hc of the ultrafine powder was smaller than that of the conventional powder. The rare earth element content (Nd + Pr) was lower in the ultrafine powders than in the conventional powder. These results indicate that the rare earth element content was insufficient in the ultrafine powders.
AB - This paper reports the effects of annealing on the magnetic properties of ultrafine Nd-Fe-B powders with an average particle size of 0.67 μm. The powder was fabricated from hydrogenation-disproportionation-desorption-recombination (HDDR)-treated Nd-Fe-B alloys by hydrogen decrepitation and helium jet milling. The coercivity of the ultrafine powders was slightly increased by annealing below 500°C, and was drastically increased by annealing above 600°C. These two stepwise increases in coercivity were attributed to hydrogen desorption and formation of a liquid Nd-rich phase. In addition, after annealing below 500°C, the coercivity (μ0Hc) of the ultrafine powder was higher than that of the conventional powder, which was prepared from a strip-cast Nd-Fe-B alloy power with a particle size of 1.12 μm, because of a decrease in particle size. In contrast, after annealing above 600°C, the μ0Hc of the ultrafine powder was smaller than that of the conventional powder. The rare earth element content (Nd + Pr) was lower in the ultrafine powders than in the conventional powder. These results indicate that the rare earth element content was insufficient in the ultrafine powders.
KW - Annealing temperature
KW - Helium jet mill
KW - Hydrogenation-disproportionation-desorption-recombination
KW - Magnetic properties
KW - Ultrafine neodymium-iron-boron powders
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U2 - 10.2320/matertrans.MAW201402
DO - 10.2320/matertrans.MAW201402
M3 - Article
AN - SCOPUS:84907654688
SN - 1345-9678
VL - 55
SP - 1582
EP - 1586
JO - Materials Transactions
JF - Materials Transactions
IS - 10
ER -