Assessment of thermodynamic properties of alloys by combining the embedded-atom and the quasiharmonic methods

The Embedded Atom Method (EAM) was combined with the quasiharmonic approximation to determine the enthalpies and the free energies of mixing for a number of binary f.c.c. and b.c.c. metallic solid solutions. In each case, the EAM potential functions were determined using only the data for the constituent elements. It was found that when two f.c.c. elements are mixed to form an f.c.c. solid solution, the combination of the EAM and the quasiharmonic methods gives a fairly good assessment of the thermodynamic properties of the solid solution. On the other hand, when an f.c.c metal and an b.c.c. metal are combined to produce either an f.c.c. or an b.c.c solid solution, the same approach fails to predict correctly the enthalpies and the free energies of the mixing. However, at least over a composition range reasonably good predictions can still be obtained for the relative thermodynamic stability of the f.c.c. and the b.c.c. structures which is of interest in the analysis of diffusionless phase transformations, such as the martensitic transformation.