Atom probe characterization of an /spl alpha/-Fe/Nd/sub 2/Fe/sub 14/B nanocomposite magnet with a remaining amorphous phase

The microstructural features of Nd/sub 8/Fe/sub 76.5/Co/sub 8/B/sub 6/Cu/sub 0.5/Nb/sub 1/ nanocomposite magnet have been studied by a three-dimensional atom probe (3DAP) and transmission electron microscopy (TEM). The as-melt-spun microstructure is composed of /spl alpha/-Fe, Nd/sub 2/Fe/sub 14/B and a large fraction of intergranular amorphous phase. The annealed microstructure with optimum magnetic properties contains the same constituent phases as those in the as-quenched state, but the volume fraction of the Nd/sub 2/Fe/sub 14/B grains is increased by partial crystallization of the remaining amorphous phase. Nb and B are found to be enriched in the remaining amorphous phase. Unlike Fe/sub 3/B/Nd/sub 2/Fe/sub 14/B nanocomposite, Cu additions are not effective in refining the grain size in this system.