Change in Magnetic Domain Structure of Nd-Fe-B Sintered Magnets by Compressive Stress.

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. [ABSTRACT FROM AUTHOR]
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