Enhanced coercivities in die-upset Nd-Fe-B magnets with diffusion-alloyed additives (Zn, Cu, and Ni)

Abstract

Rapidly solidified Nd-Fe-B ribbons were crushed and mixed with a fine powder (10–100μm) of a pure element before hot working into fully dense anisotropic magnets. At the high temperatures and pressures required for densification some additives diffused throughout the ribbon matrix and presumably into the neodymium-rich phase surrounding the Nd2Fe14B grains. In small concentrations (0.5–0.8 wt%), zinc, copper, and nickel additions enhanced the coercivities of die-upset magnets by 100%, 77%, and 53%, respectively. Additives which did not diffuse thoroughly, such as manganese, had no measurable effect on the coercivities.