The antimony-niobium (Sb-Nb) system

A constitutional diagram was established for the Nb-Sb system in the region with more than 30 at, % Sb and below 1450 degrees C, Investigation of the phase relations was based on differential thermal analysis (DTA),light opti cal microscopy, electron probe microanalysis, and X-ray diffraction experim ents on argon are melted bulk alloys, which were annealed at 600 OC in vacu um-sealed silica capsules up to 1400 h, Differential thermal analysis runs (5 to 20 K/min, T-max = 1450 degrees C) were performed on alloys vacuum sea led in Ta crucibles with an inner lining of W, In contrast to earlier claim s for the existence of five binary phases, Nb3Sb, Nb3Sb2, NbSb, Nb5Sb4 (or Nb4Sb3), and NbSb2, the authors observed only three binary compounds: Nb3Sb , Nb5Sb4, and NbSb2, These compounds are essentially line compounds at thei r stoichiometric composition and without a significant homogeneity region a t 600 degrees C. All compounds are formed by peritectic reactions: L + (Nb) <----> Nb3Sb (1750 +/- 25 degrees C, (L congruent to 55 at,% Sb), L + Nb,S b <----> Nb5Sb4 (1320 +/- 10 degrees C, L congruent to 71 at. % Sb), and L + Nb5Sb4 <----> NbSb2 (1180 +/- 10 degrees C, L congruent to 88 at. % Sb), The system is characterized by a depleted eutectic reaction L <----> (Sb) NbSb2 at 618 +/- 8 degrees C and L congruent to 99 at. % Sb.