Thermodynamic investigations in the Al–Fe system: Thermodynamic modeling using CALPHAD

Abstract The Al–Fe system has been modeled and optimized with the CALPHAD approach. Heat capacity values from three intermetallic phases (stoichiometric compositions: Al 2 Fe, Al 5 Fe 2 and Al 13 Fe 4 ) were experimentally determined and implemented into the Gibbs energy descriptions, thus the estimated heat capacity from Neumann–Kopp is substituted. From these results together with new literature values, a revised dataset of the binary Al–Fe system is presented. Based on the Compound Energy Formalism, the homogeneity range of the Al 2 Fe and Al 5 Fe 2 phase is represented using a two-sublattice model. In addition, the Al 8 Fe 5 phase has been modeled with a four-sublattice model and the number of sublattices of the Al 13 Fe 4 phase has been changed from a three-sublattice model to a two-sublattice model. The critically assessed parameters provide a consistent thermodynamic dataset and represent most of the relevant thermochemical data as well as phase diagram data within their experimental uncertainties.