The microstructures of a Nd8Fe76.5Co8B6Nb1Cu0.5 nanocomposite magnet have been investigated by transmission electron microscopy and three-dimensional atom probe microanalysis. The ribbon prepared by the single roller melt-spinning process under an optimal cooling rate was partially crystallized, being composed of alpha-Fe, Nd2Fe14B, and the intergranular amorphous phase. The volume fraction of the Nd2Fe14B phase increases by annealing at 740 degrees C for 3 min, but a small amount of amorphous phase remains in the intergranular region. Atom probe results show Nb and B are significantly enriched in the remaining amorphous phase, which would be the reason for the high thermal stability of the remaining amorphous phase. Cu atoms are dissolved in the Nd2Fe14B phase during solidification, and they do not have much influence on the microstructural evolution. (C) 2000 American Institute of Physics. S0021-8979(00)09112-X. References: 17
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