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.