Thermodynamic assessment of the Al-Cu-Zn system, part I: Cu-Zn binary system

The thermodynamic description of the Cu-Zn system is reassessed based on all original experimental data. Previous work on that subject is critically analyzed and the need for improvement is worked out. Tracing back to the original experimental data, the δ phase is acknowledged as hexagonal structure and thus modeled as a separate phase from the Bcc phase. An improved quantitative description of original experimental phase equilibrium and thermodynamic data for Zn-rich alloys is achieved without sacrificing the quality of description in the full composition range. The new γ phase model reflects the crystal structure and facilitates extension to ternary systems. The earlier suggested temperature dependence of the enthalpy of mixing in the liquid phase is shown to be deduced from derived data of vapor pressure and chemical potential in a narrow temperature range and is, thus, disapproved.