Sintering of Nd-Fe-B Magnets from Dy Coated Powder

Abstract

High-coercive (Nd,Dy)-Fe-B magnets were fabricated via dysprosium coating on Nd-Fe-B powder. The sputtering coating process of Nd-Fe-B powder yielded samples with densities greater than 98%. (Nd,Dy)2Fe14B phases may have effectively penetrated into the boundaries between neighboring Nd2Fe14B grains during the sputtering coating process, thereby forming a (Nd,Dy)2Fe14B phase at the grain boundary. The maximum thickness of the Dy shell was approximately 70 nm. The maximum coercivity of the Dy sputter coated samples(sintered samples) increased from 1162.42 to 2020.70 kA/m. The microstructures of the (Nd,Dy)2Fe14B phases were effectively controlled, resulting in mproved magnetic properties. The increase in coercivity of the Nd-Fe-B sintered magnet is discussed from a micro- structural point of view.