Estimation of the thermodynamic parameters of second-order interactions in binary alloys on the basis of experimental thermodynamic data

The values of the thermodynamic parameters of second-order interaction in dilute binary substitutional solid solutions have been estimated for twenty seven systems on the basis of experimental thermodynamic data. The possibilities are outlined of using these data for checking the results of the first-principles calculations of the electronic theory of alloys. It has been established that for the majority of the systems examined the sign of the parameter of second-order interaction is opposite to that of the Wagner parameter of interaction. For the solid solutions of molybdenum in chromium at a temperature of 1471 K the values of the thermodynamic parameter of the second-order interaction and first-order enthalpy parameter are connected with the value of the Wagner parameter of interaction via formulas, which correspond to the model in which three-particle interaction is absent and the radius of pairwise interaction corresponds to the nearest coordination shell. The potential of pairwise interaction is temperature-independent. For the solid solutions of platinum in cobalt at a temperature of 1273 K, the value of the Wagner parameter of interaction calculated in the approximation of an Ising Hamiltonian with the use of effective pairwise interactions evaluated in the literature by the methods of the electronic theory of alloys agree in sign and in order of magnitude with the experimental value.