Diffusion processes in hot-deformed Nd-Fe-B magnets with DyF3 additions

Nd-Fe-B melt spun ribbons have been hot-compacted and subsequently die-upset together with DyF3 in order to increase coercivity in nanocrystalline hot-deformed magnets. Magnetic measurements reveal enhanced coercivities for low and reduced coercivities for high Dy-fractions. This behaviour is due to a superposition of the formation of (Dy,Nd)(2)Fe14B and non-magnetic Dy and Nd fluoride and oxide phases. Energy dispersive and wavelength dispersive X-ray elemental maps verified this feature. Heat treatments at 600 degrees C induce a strong F diffusion along the flake boundaries without inducing grain growth. This diffusion is correlated with the changes in magnetic properties.