Thermodynamic modeling of the quaternary Al-Cu-Mg-Si system

Abstract

Based on the critically evaluated thermodynamic and phase diagram information available in the literature, thermodynamic modeling of the Cu-Mg, Al-Cu-Mg, Al-Cu-Si, and Cu-Mg-Si systems were conducted using the CALPHAD (CALculation of PHAse Diagrams) technique. The liquid phase was described using the Modified Quasi-chemical Model (MQM), and the solid solution phases were modeled with the Compound Energy Formalism (CEF). Based on the newly obtained and the previously published thermodynamic descriptions of the subsystems, a set of self-consistent thermodynamic description for the Al-Cu-Mg-Si quaternary system was constructed. Comprehensive comparison between the calculated and measured thermodynamic and phase diagram information indicated that most of the reliable experimental data in the quaternary system can be satisfactorily reproduced by the presently obtained thermodynamic description. The optimized thermodynamic parameters can be used for the calculations of the phase diagram and thermodynamic properties of any composition and temperature range in the Al rich Al-Cu-Mg-Si quaternary system.