Thermodynamic modeling of the Pd–Sb system

The Pd–Sb binary system has been thermodynamically assessed by means of CALPHAD approach. The Redlich–Kister polynomial was used to describe the solution phases, liquid (L) and fcc. The non-stoichiometric compound Pd3Sb and Pd5Sb3 were described by a two-sublattice model (Pd,Sb)3Sb and (Pd,Sb)5(Pd,Sb)3. The six intermetallic compounds, Pd8Sb3, Pd20Sb7, Pd5Sb2, Pd2Sb, PdSb and PdSb2, were treated as stoichiometric phases. The parameters of the Gibbs energy expressions were optimized according to all the available experimental information of both the equilibrium data and the thermodynamic results. A set of self-consistent thermodynamic parameters of the Pd–Sb system has been obtained. The calculations agree well with the respective experimental data.

Research highlights▶ This paper provides the first thermodynamic assessment of the Pd–Sb binary system, which is important for ohmic contact materials. A consistent set of thermodynamic parameters that reproduce well the phase diagram and thermodynamic information is obtained in this study.