Die-upset hybrid Pr-Fe-B nanocomposite magnets

Anisotropic nanocomposite R-Fe-B/Fe magnets (R=Pr, Tb) were synthesized by hot pressing and subsequent die upsetting blends of R-rich and R-lean melt-spun ribbons. The magnets have a layered structure, in which alternating layers of the two starting alloys lay perpendicularly to the pressing direction. A crystallographic alignment of the R2Fe14B grains is observed in the R-rich layers, whose microstructure is identical to that of the conventional die-upset magnets. The R-lean layers consisting of exchange-coupled R2Fe14B and alpha-Fe grains retain the random crystallographic orientation. The obtained bulk R-lean magnets show better properties than magnets of the same overall composition prepared from a single alloy. (C) 2004 American Institute of Physics.