Effect of DyF3 additions on the coercivity and grain boundary structure in sintered Nd–Fe–B magnets

Coercivity of Nd–Fe–B sintered magnets was obviously enhanced by DyF 3 additions with little sacrifice of remanence and squareness factor. An ordered rare-earth oxyfluoride grain boundary phase containing ∼30 at.% F was formed. In addition, the presence of F decreased the thickness of the region of reduced anisotropy of the Nd 2 Fe 14 B grain. Dy segregated on the surface of the Nd 2 Fe 14 B grains. The individual effects of F and Dy elements on the increased coercivity are discussed based on these results.