Effects of DyH_x and Dy_2O_3 powder addition on magnetic and microstructural properties of Nd-Fe-B sintered magnets

摘要

The magnetic and microstructural properties of (Nd_(27.68)Dy_(4.89))-Fe_(bal).B_(1.0)M_(2.4) (wt. %, M = Cu, Al, Co, and Nb) sintered magnets doped with Dy_2O_3 and DyH_x powders were studied. The coercivity of the DyH_x-doped magnet improved, with no change in the remanence. Well-developed core-shell microstructures were seen in the DyH_x-doped magnet, as compared to the case of the Dy_2O_3-doped magnet. Diffusion of Dy was enhanced in the DyH_x-doped magnet, probably because dissolution of hydrogen in Nd_2Fe_(14)B increased the lattice parameter. The (00L) grain alignment in the DyH_x-doped magnet was also improved.