THEORETICAL CALCULATION OF THERMODYNAMIC DATA FOR BCC BINARY-ALLOYS WITH THE EMBEDDED-ATOM METHOD

The dilute-limit heats of solution for all binary alloys of six bcc transition metals (V, Nb, Ta, Mo, W, and Fe) have been calculated with the analytic embedded-atom model for bcc pure metals by Johnson and Oh. Cubic equations are proposed and used for providing a smooth cutoff for the calculated potential and electron density functions between second- and third-nearest neighbors in the calculation. The heats of formation for all of the binary alloys of these six bcc metals for the whole compositional range and the intermetallic compounds A3B, AB, and AB3 are also calculated. The dilute-limit heats of solution are generally in agreement with available experimental values except for Ta in W and W in Ta. The heats of formation agree well with available experimental data, ab initio calculations by Colinet, Beesound, and Pasturrel, and thermodynamic calculations with the Miedema model for Mo-Ta, Mo-Nb, and Fe-V. The heats of formation are in good agreement with thermodynamic calculations with the Miedema model for W-V, Nb-V, Ta-V, Fe-W, Mo-W, Ta-Nb, Fe-Nb, Fe-Ta, and Mo-V alloy systems. There are, however, significant differences between the heats of formation for the present work and calculations with the Miedema model for the Ta-W, Nb-W, and Fe-Mo alloy systems.