Enthalpies of formation of AlFe: Experiment versus theory

Enthalpies of formation for AlFe were determined by solution calorimetry over a wide concentration range (XAl=0.40–0.50) and over a wide temperature interval (T = 296 to 1029 K). The value of enthalpy of formation becomes more negative with deviations from the stoichiometric composition. The temperature dependence of the experimental enthalpy exhibits an unusual maximum of its value at intermediate temperatures. These results will be discussed in relation to ab initio calculations, with particular attention to the spin polarisation energy of elemental Fe and the influence of the magnetic properties of Fe on the correct choice of reference state for paramagnetic AlFe.