A thermodynamic description of the Al–Fe–Si system over the whole composition and temperature ranges via a hybrid approach of CALPHAD and key experiments

Abstract

A consistent thermodynamic data set for the Al–Fe–Si system over the entire composition and temperature ranges is obtained by using CALPHAD approach applied to predominant literature data, supplemented with the present experimental data resulting from X-ray diffraction, differential thermal analysis, electron probe microanalysis, and enthalpy measurements of decisive alloys. Numerous comparisons between the calculated and measured phase diagrams as well as thermodynamic quantities indicate that almost all of the reliable experimental information is satisfactorily accounted for by the present thermodynamic modeling. The inconsistency between the measured and computed enthalpies of formation via CALPHAD method for the ternary compounds is traced to the Fe–Si system in which there is a disagreement between the experimental enthalpy of formation and CALPHAD type one. The reliability of calculated thermodynamic properties for ternary phases is verified through enthalpy measurement employing drop calorimetry. A hybrid approach of CALPHAD method and key experiment to acquire a thermodynamic description of a complex ternary system is recommended.