Currently, many attempts have been taken to enhance the coercivity and reduce the heavy rare-earth consumption of Nd–Fe–B sintered magnets simultaneously. Some progresses have been made in efforts to introduce Dy and/or Tb in many forms, namely, oxides, fluorides, hydrides, intermetallic compounds and alloys. The Tb3Co0.6Cu0.4 composition was suggested to apply it as the efficient addition in manufacturing sintered Nd-Fe-B-based magnets. The alloy was prepared by arc melting in purified argon atmosphere, annealed at 600 C for 90 h and subsequently subjected to hydrogenation. The phase composition and structure of the initial and hydrogenated alloy were studied by electron microscopy, electron microprobe and X-ray diffraction analyses. The in part substitution of copper for cobalt does not change the orthorhombic Fe3C-type structure (space group Pnma) of the Tb3Co compound. The copper solubility in the Tb3Co and Tb12Co7 compounds was determined and the lattice parameters of the compositions were estimated. During hydrogenation, the Tb3Co0.6Cu0.4 composition was shown to decompose into TbH2-3 hydride and fine dispersed (Co, Cu) mixture. Additions of the hydrogenated compound to Nd-Fe-B-based sintered magnets (the initial composition (wt.%) is Nd-24.0, Pr-6.5, Dy-0.5, B-1.0, Al-0.2, Fe-balance was prepared by strip-casting technique and subjected to hydrogen decrepitation) allow us to manufacture magnets with Br = 1.35 T and jHc = 1336 kA/m.Keywords: Co-Cu-Tb intermetallics, microstructure, hydrogenation, Nd-Fe-B magnets
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