Anisotropic hot deformed magnets prepared from Zn-coated MRE-Fe-B ribbon powder (MRE = Nd+Y+Dy).

Milled melt-spun ribbon flake of MRE-Fe-B coated with Zn coating using a vapor transport technique was found to have significant increase in coercivity without degrading the magnetization when the Zn thickness and heat treatment were optimized. Magnetic measurements show that 0.5-1 wt.% Zn coating increases the coercivity about 1 kOe over the initial ribbon powder. After vacuum hot deformation (VHD), the VHD magnet with Zn coating of 0.5 wt.% results in a nearly 3 kOe higher coercivity than an un-coated alloy magnet. An optimized VHD magnet with 0.5 wt.% Zn coating obtains a coercivity of 11.2 kOe and (BH)_max of 23.0 MGOe, respectively. SEM and TEM microstructures analysis demonstrates that the Zn coating on the surface of ribbon powder has diffused along the intergranular boundaries after the ribbon powder was annealed at 750 °C for 30 min or was hot deformed at 700-750°C. [ABSTRACT FROM AUTHOR]