A thermodynamic assessment of Ni–Sb system

Abstract

The Ni–Sb system was critically assessed by means of the CALculation of PHAse Diagram (CALPHAD) technique. The solution phases, Liq and (αNi), were modelled as the substitutional solutions with the Redlich–Kister equation. The intermediate phases, (γNiSb) and (βNi 3Sb), with homogeneity ranges were described respectively using three-sublattices (Sb) 1/3(Ni%,V a) 1/3(V a%,Ni) 1/3 and (Sb) 1/4(Ni%,V a) 1/2(Ni%,V a) 1/4 based on their structure features. Corresponding to the phase (βNi 3Sb), the two low-temperature phases of (δNi 3Sb) and (θNi 5Sb 2) with narrow homogeneity ranges were modelled as two-sublattice, (Ni) 3/4(Sb,Ni) 1/4 and (Ni) 5/7(Sb,Ni) 2/7. The intermetallic compound ζNiSb 2 with no homogeneity ranges was treated as stoichiometric compound. The phase ε Sb was considered as pure Sb for the solubility of Ni in ε Sb is very low. A set of self-consistent thermodynamic parameters of the Ni–Sb system was obtained. The optimized phase diagram and thermodynamic properties were presented and compared with experimental data.