Thermodynamic modeling of the In–Pt system

By means of the CALPHAD (CALculation of PHAse Diagram) technique, the In–Pt system was critically assessed. Three solution phases (liquid, face-centered cubic, tetragonal) were described with the substitutional solution model. The compounds In7Pt3, In2Pt, In3Pt2, InPt2 and αIn2Pt3 were treated as stoichiometric compounds. The compounds InPt, In5Pt6, In9Pt13 and βIn2Pt3, which have a homogeneity range, were treated as the formulae (In,Pt)(In,Pt), (In,Pt)5(In,Pt)6, In9(In,Pt)13 and (In,Pt)2(In,Pt)3, respectively. A two-sublattice model (In,Pt)0.25(In,Pt)0.75 is applied to describe the compound InPt3 in order to cope with the order–disorder transition between InPt3 with AuCu3-type structure (L12) and face-centered cubic solution (A1). A set of self-consistent thermodynamic parameters describing the Gibbs energy of each individual phase as a function of composition and temperature for the In–Pt system was obtained.