Theoretical calculation of thermodynamic data for gold-rare earth alloys with the embedded-atom method

The thermodynamic data, such as the formation enthalpies of disordered solid solutions and intermetallic compounds, and the lattice parameters in the RE-Au (RE = Sc, Y, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er) systems are calculated with the modified analytical embedded atom method (EAM). This work has been undertaken to investigate systemically in RE-Au alloying energies, and to augment available calorimetric data for enthalpies of formation in support of the development of accurate multicomponent thermodynamics databases for these technologically interesting systems. The accuracy of our calculations is assessed through comparisons with the experimental measurements and the theoretical results from the first-principles VASP as well as Miedema's theory. The composition dependence of the heats of formation for these 10 binary systems is similar, and there is a minimum at 50 at.%Au for REAu (CsCl-type) ordered phase. In all 10 binary systems, the calculated zero-temperature intermetallic formation energies generally agree well with the calorimetric data obtained by the direct reaction synthesis and/or VASP results except for REAu2 (MoSi2-type) phase. For the intermetallic phase, the calculated EAM and VASP zero-temperature lattice parameters agree well with the experimental data at ambient temperature. The largest discrepancy between the EAM calculated lattice parameters and experimental data [K. Fitzner, W.G. Jung, O.J. Kleppa, Metall. Trans. A 22 (1991) 1103 [16]; K. Fitzner, O.J. Kleppa, Metall. Trans. A 24 (1993) 1827 [17]; K. Fitzner, O.J. Kleppa, Metall. Trans. A 25 (1994) 1495 [18]; R. Ferro, G. Borzone, N. Parodi, J. Alloys. Compd. 321 (2001) 248 [19]] is approximately 10-18% for some intermediate phases, such as REAu (CrB-type) and RE3Au4 (Pu3Pd4-type).