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 DyF3 additions with little sacrifice of remanence and squareness factor. An ordered rare-earth oxyfluoride grain boundary phase containing similar to 30 at.% F was formed. In addition, the presence of F decreased the thickness of the region of reduced anisotropy of the Nd2Fe14B grain. Dy segregated on the surface of the Nd2Fe14B grains. The individual effects of F and Dy elements on the increased coercivity are discussed based on these results. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.