High-energy product Nd-Fe-B permanent magnets

We have explored the hard magnetic properties of melt-spun Nd-Fe-B alloys. A maximum energy product of 14.1 MG Oe has been observed, the highest value ever reported for a light rare earth-iron material. X-ray analyses indicate that the alloys exhibiting optimum characteristics are comprised of roughly spherical crystallites of an equilibrium Nd-Fe-B intermetallic phase. The observed grain sizes are in or near the estimated single-domain range, suggesting that the coercivity arises principally from the formation of single-domain particles.