TY - JOUR
T1 - Estimation of demagnetization curve of magnet with nonuniform coercivity
AU - Tokushige, Takayuki
AU - Umabuchi, Masafumi
AU - Miyagi, Daisuke
AU - Takahashi, Norio
AU - Ito, Masaru
AU - Hirota, Koichi
PY - 2012/2/13
Y1 - 2012/2/13
N2 - Neodymium-iron-boron (Nd-Fe-B) magnets exhibit exceedingly high maximum energy products and remanences. Their coercivities, however, decrease rapidly with increasing the temperature, and the magnets are easily demagnetized at elevated temperatures. To reduce the effects of temperature, the coercivity at the room temperature is enhanced by the addition of the dysprosium (Dy), which causes a reduction in remanence. The Grain Boundary Diffusion process is a technology to enhance coercivities while suppressing a large reduction in remanences. Dy that is effective for the coercivity enhancement is supplied from the magnet surface and diffused into the magnets through the grain boundary phase, and then put at the grain surface. When the Grain Boundary Diffusion process is applied to relatively large magnets, the partial coercivities near the magnet surface, where higher coercivities are generally required, can be enhanced effectively. In other words, the magnets exhibit nonuniform coercivity. We have conceived a simple and effective method for estimating the demagnetization curves of such nonuniform coercivity magnets. In this paper, the validity of the estimation method was examined.
AB - Neodymium-iron-boron (Nd-Fe-B) magnets exhibit exceedingly high maximum energy products and remanences. Their coercivities, however, decrease rapidly with increasing the temperature, and the magnets are easily demagnetized at elevated temperatures. To reduce the effects of temperature, the coercivity at the room temperature is enhanced by the addition of the dysprosium (Dy), which causes a reduction in remanence. The Grain Boundary Diffusion process is a technology to enhance coercivities while suppressing a large reduction in remanences. Dy that is effective for the coercivity enhancement is supplied from the magnet surface and diffused into the magnets through the grain boundary phase, and then put at the grain surface. When the Grain Boundary Diffusion process is applied to relatively large magnets, the partial coercivities near the magnet surface, where higher coercivities are generally required, can be enhanced effectively. In other words, the magnets exhibit nonuniform coercivity. We have conceived a simple and effective method for estimating the demagnetization curves of such nonuniform coercivity magnets. In this paper, the validity of the estimation method was examined.
KW - Coercivity distribution magnet
KW - Estimation of demagnetization curve
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U2 - 10.1541/ieejfms.132.101
DO - 10.1541/ieejfms.132.101
M3 - Article
AN - SCOPUS:84856694913
VL - 132
SP - 101
EP - 107
JO - IEEJ Transactions on Fundamentals and Materials
JF - IEEJ Transactions on Fundamentals and Materials
SN - 0385-4205
IS - 1
ER -