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Change in Magnetic Domain Structure of Nd‐Fe‐B Sintered Magnets by Compressive Stress
Author(s) -
TAKEZAWA MASAAKI,
MORIMOTO YUJI,
EJIMA JUN,
NAKANO YOSHIKAZU,
ARAKI TAKESHI
Publication year - 2018
Publication title -
electrical engineering in japan
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.136
H-Index - 28
eISSN - 1520-6416
pISSN - 0424-7760
DOI - 10.1002/eej.23058
Subject(s) - coercivity , demagnetizing field , materials science , magnet , compressive strength , residual stress , magnetic domain , compression (physics) , stress (linguistics) , composite material , condensed matter physics , nuclear magnetic resonance , magnetization , magnetic field , mechanical engineering , physics , linguistics , philosophy , quantum mechanics , engineering
SUMMARY To clarify the relationship between compressive stresses and demagnetization of Nd‐Fe‐B sintered magnets, we have examined the change in domain configuration by compressive stresses using a Kerr microscope. The magnetic domains of five kinds of Nd‐Fe‐B sintered magnets have been observed. The magnets have a coercivity of 0.8 MA/m to 1.4 MA/m and residual magnetic flux density of 1.3 T to 1.5 T. Irreversible demagnetization of Nd‐Fe‐B magnets with a low coercivity of 0.875 MA/m and high residual magnetic flux density of 1.41 T to 1.47 T have occurred from applying a compressive stress of 100 MPa. The compression‐affected area is approximately 0.14%. The stress more than 50 MPa is needed to demagnetize Nd‐Fe‐B magnets. The amount of irreversible demagnetization depends upon the intensity of the compressive stress as well as the residual magnetic flux and coercive force of the magnets.