CuPt alloys have been investigated intensively in there years because of their applications for catalysts as an alternative to Pt-catalyst. Moreover, recently Takahashi et al. has found that Cu addition is effective to decrease the ordering temperature in the fabrication process of L1₀-FePt(-Cu) nano-magnetic materials, which results in growing interest of Cu-Pt system.

   In the present study, the Cu-Pt binary system is assessed by means of the CALPHAD technique. The four and two sublattice models were applied to describe the Gibbs energy of L1₂ and FCC, and L1₁, respectively. Liquid phase is models as a substitutional solution. In the present assessment, the effect of the short range ordering(SRO) is taken into account through the reciprocal parameters. The contribution of SRO to the free energy for the four sublattice model can be described as G_m^SRO = -3z⁰P²_Cu:Ptw²_Cu:Pt/RT where G_m^SRO, ⁰P_Cu:Pt, w_Cu:Pt, z, R, and T are the contribution of SRO to the Gibbs energy, Cu-Pt pair probability, interaction energy between Cu and Pt atoms, coordination number(z=4), Gas constant, and temperature in kelvin, respectively.

   A consistent set of parameters for the phases in this system was obtained. The assessment satisfactorily reproduces the experimental phase equilibria and thermodynamic properties: enthalpies, activity of Cu and long and short range order parameters.