TY - JOUR
T1 - Coercivity enhancement of hot-deformed Nd-Fe-B magnets by the eutectic grain boundary diffusion process
AU - Liu, Lihua
AU - Sepehri-Amin, H.
AU - Ohkubo, T.
AU - Yano, M.
AU - Kato, A.
AU - Shoji, T.
AU - Hono, K.
N1 - Funding Information:
This work was in part supported by JST, CREST and the future pioneering program ‘‘Development of magnetic material technology for high-efficiency motors” commissioned by the New Energy and Industrial Technology Development Organization (NEDO) . Lihua Liu acknowledges NIMS for the provision of the NIMS Junior Research Assistantship.
Publisher Copyright:
© 2016 Elsevier B.V. All rights reserved.
PY - 2016/5/5
Y1 - 2016/5/5
N2 - Nd-M (M = Al, Cu, Ga, Zn, Mn) alloys with compositions close to eutectic points were investigated as diffusion sources for the grain boundary diffusion process to hot-deformed Nd-Fe-B magnets. Coercivity enhancement was observed for most of the alloys. Among them, the sample processed with Nd90Al10 exhibited the highest coercivity of 2.5 T at room temperature. However, the sample processed with Nd70Cu30 exhibited the highest coercivity of 0.7 T at 200 °C. Microstructural observations using scanning transmission electron microscope (STEM) showed that nonferromagnetic Nd-rich intergranular phase envelops the Nd2Fe14B grains after the diffusion process. Abnormal grain growth and the dissolution of Al into the Nd2Fe14B grains were observed in the sample processed with Nd90Al10, which explains its inferior thermal stability of coercivity compared to the sample processed with Nd70Cu30. The coercivity enhancement and poor thermal stability of the coercivity of the Nd90Al10 diffusion-processed sample are discussed based on microstructure studies by transmission electron microscopy.
AB - Nd-M (M = Al, Cu, Ga, Zn, Mn) alloys with compositions close to eutectic points were investigated as diffusion sources for the grain boundary diffusion process to hot-deformed Nd-Fe-B magnets. Coercivity enhancement was observed for most of the alloys. Among them, the sample processed with Nd90Al10 exhibited the highest coercivity of 2.5 T at room temperature. However, the sample processed with Nd70Cu30 exhibited the highest coercivity of 0.7 T at 200 °C. Microstructural observations using scanning transmission electron microscope (STEM) showed that nonferromagnetic Nd-rich intergranular phase envelops the Nd2Fe14B grains after the diffusion process. Abnormal grain growth and the dissolution of Al into the Nd2Fe14B grains were observed in the sample processed with Nd90Al10, which explains its inferior thermal stability of coercivity compared to the sample processed with Nd70Cu30. The coercivity enhancement and poor thermal stability of the coercivity of the Nd90Al10 diffusion-processed sample are discussed based on microstructure studies by transmission electron microscopy.
KW - Coercivity
KW - Diffusion process
KW - Grain boundary phase
KW - Nd-Fe-B
KW - Permanent magnets
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U2 - 10.1016/j.jallcom.2015.12.227
DO - 10.1016/j.jallcom.2015.12.227
M3 - Article
AN - SCOPUS:84957016322
VL - 666
SP - 432
EP - 439
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
SN - 0925-8388
ER -