The Nd-Fe-B materials for permanent magnets

Abstract The microstructure-magnetic property relationship in Nd-Fe-B-type permanent magnetic materials has been investigated by means of transmission electron microscopy and analyses of the temperature dependence of the intrinsic coercivity. Effects of postsintering heat treatment, mean grain size in sintered magnets, magnetic separation of the magnetic grains by non-magnetic phases, and the degree of alignment of the c -axis of the magnetic grains have been studied in permanent magnets based on Pr 2 Fe 14 B. Results indicate that local demagnetization fields are the main sources of a reduction of the intrinsic coercivity in this type of magnets.

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