Crystallization of Co-containing Finemet alloys

Fe73.5-xCoxSi13.5B9Cu1Nb3 (x = 13.5 and 60 at.%) materials with different v olumetric fractions of nanometer-sized (Fe, Co)Si crystallites produced by controlled crystallization of the amorphous alloy, were studied by combinin g Fe-57 Mossbauer spectrometry (MS) and X-ray diffraction (XRD). The crysta lline fractions were first estimated and the compositions of both the amorp hous residual phase and the nanocrystalline phase were modelled. The compos ition of the (Fe, Co)Si nanosized crystals does not change with the crystal line fraction but depends on the amorphous composition. Lattice parameters, hyperfine fields and Curie temperatures data are consistent with the propo sed composition. (C) 2001 Elsevier Science B.V. All rights reserved.