CHARACTERIZATION OF PHASES IN THE FE-NB SYSTEM

The Fe-Nb system was investigated by means of X-ray diffraction and Mo ssbauer spectroscopy (at 300 and 77 K), in the range from 1 to 66.7 at %. We have found that the limit of solubility of Fe in Nb at 1100-degr ees-C is between 3 and 4 at% Fe, and observed the coexistence of the N b solid solution (Nbss) phase and Fe21Nb19 in the range from 4 to 40 a t% Fe. The Mossbauer parameters of all the single phases are reported. The lattice parameters of Nbss phase present no significant variation with the Nb content. The X-ray pattern for the Fe21Nb19 phase could n ot be solved. The Laves phase Fe2Nb presents Mossbauer and X-ray param eters that agree with the literature.