Nd 2 Fe 14 B -based nanocomposite magnets with transition metal and carbon additions

Abstract

Nanocomposite intermediate rare-earth∕high-boron content hard magnetic alloys, having compositions Nd 9 Fe 73 B 12.6 C 1.4 M 4 ( M = Ti , V, Cr, Zr, or Nb), have been produced as melt spun ribbon. As for the Ti addition, all the other solutes were effective in modifying the crystallization behavior so that the Nd 2 Fe 14 B phase formed rather than the cubic Nd 2 Fe 23 B 3 phase. The magnetic properties of the V-, Cr-, Zr-, and Nb-containing alloys in the as-spun state and following annealing are compared with those of the Ti-containing alloy. Good combinations of intrinsic coercivity ( 1020 kA m − 1 ) and of maximum energy product ( 97 kJ m − 3 ) were obtained for the V-containing alloy, closely comparable with those for the M = Ti alloy, and the Zr addition also yielded a good property combination.