Formation enthalpies of Fe–Al–RE ternary alloys calculated with a geometric model and Miedema's theory

A method to estimate the thermodynamic properties of ternary alloys from those of constitutive binary alloys was proposed. The thermodynamic data of binaries were calculated by Miedema's theory. The asymmetry of constitutive binary alloys in the ternary system was considered in the present extrapolating procedure. The dependence of asymmetric constituent on the choice in Toop's model was overcome. The present method was used to calculate the formation enthalpies of Fe–Ni–V alloys. The agreement between the calculation and experiment is reasonable. So the formation enthalpies of Fe–Al–RE (RE = lanthanide metal) ternary alloys were calculated with the present method. The relative stability of RE(Fe1−xAlx)13, RE2(Fe1−xAlx)17 and RE5(Fe1−xAlx)17 were also studied with the present method.