High-coercivity Nd-Fe-B-type permanent magnets with less dysprosium

The effects of V or Mo addition on the microstructure and magnetic properties of Nd-Dy-Fe-Co-B sintered magnets were studied experimentally. It is shown that these additives increase the intrinsic coercivity of cobalt-containing Nd-Fe-B-type sintered magnets, serving to reduce the amount of Dy required for thermal stability. Corrosion resistance in a humid atmosphere is also improved by these elements. It is concluded that V or Mo addition in sintered magnets make it possible to achieve the thermal stability and corrosion resistance required in applications which encounter high-temperature and high-humidity environments and in which a high remanence is of secondary importance.<
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