BEHAVIORS OF GA DURING CRYSTALLIZATION OF AMORPHOUS ND4.5FE73GA1CO3B18.5 BY FLUORESCENCE XAFS

Combined addition of Ga and Co into Fe3B-based Nd-Fe-B hard magnetic m aterials improves squareness of hysteresis loop and remanence. Since G a addition is believed to reduce the grain size of the crystallites pr ecipitated from the as-quenched amorphous state, fluorescence XAFS mea surements of the Ga K-edge are carried out. A small change of XAFS spe ctrum for the as-quenched (amorphous) state just after the Fe3B precip itation suggests that Ga is excluded from Fe3B crystallites to surroun ding amorphous region. Good agreement of the observed XAFS spectra for the annealed at a higher temperature where Nd2Fe14B is precipitated w ith the calculated CsCl-type CoGa alloy indicates a preferential bondi ng between Ga and Co.