Thermodynamic modeling of the In–Pt system

Abstract

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 In 7Pt 3, In 2Pt, In 3Pt 2, InPt 2 and αIn 2Pt 3 were treated as stoichiometric compounds. The compounds InPt, In 5Pt 6, In 9Pt 13 and βIn 2Pt 3, which have a homogeneity range, were treated as the formulae (In,Pt)(In,Pt), (In,Pt) 5(In,Pt) 6, In 9(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 InPt 3 in order to cope with the order–disorder transition between InPt 3 with AuCu 3-type structure (L1 2) 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.