The antimony-iron-niobium (Sb-Fe-Nb) system

Phase equilibria were established in the Nb-Fe-Sb ternary system for an isothermal section at 600 °C. Investigation of the phase relations was based on light optical microscopy, electron probe microanalysis, and X-ray diffraction experiments on arc-melted bulk alloys, which were annealed up to 1400 h. One ternary compound was observed: NbFeSb (MgAgAs type) without a significant homogeneity region at 600 °C. Except for NbFe_2−y , mutual solid solubilities at 600 °C were found to be very low, for example, <1 at.% Fe and <1 at.% Nb in the binary Nb antimonides and Fe antimonides, respectively. The binary Laves phase NbFe_2−y with the MgZn₂ type exhibits an extended homogeneity region dissolving at 600 °C up to 7 at.% Sb in the ternary without change of its structure type.