Impact of TbF3 diffusion on coercivity and microstructure in sintered Nd-Fe-B magnets by electrophoretic deposition

Abstract Using electrophoretic deposition (EPD) method, the optimum diffusion temperature of TbF 3 EPD-coated sintered Nd–Fe–B magnets was clarified. During the grain boundary diffusion, the coercivity increased gradually from 1241 to 1946 kA/m then decreased with increasing the effective TbF 3 content coated on the surface of the magnets. Microstructure analysis suggested that the coercivity was closely related to the concentration and the distribution of Tb. Mechanism of coercivity enhancement due to the Tb diffusion is discussed based on the observation.