Thermodynamic modeling of the Cu-Si system

The thermodynamic description of the Cu-Si system has been updated with first-principles calculations of the ε{lunate}-Cu₁₅Si₄ phase and solid solution phases. Calculated enthalpy of formation for the ε{lunate}-phase indicates that enthalpies of formation for intermetallic compounds in Cu-Si must be negative, which were evaluated as positive in the previous thermodynamic modelings. Enthalpies of mixing for the solid solution phases, bcc, fcc, and hcp, are also calculated from first-principles study of Special Quasirandom Structures (SQS) and all the solution phases exhibit similar mixing behavior. It is concluded that first-principles calculations of solid phases including solution phases can supplement scarce experimental data and be readily used in thermodynamic modelings.