At first, this does not seem such a remote goal: all the physical principles governing phase stability are known. However, modeling those physical principles in all their details quickly becomes intractable with today's computers. Merely waiting for computers to become fast enough is not an option: some of today's problems would only be solvable in a hundred years...
Hence, we are forced to use approximations to be able to obtain results in a reasonable time. Physical insight about the problems to be solved can lead to reliable approximations that drastically reduce the amount of calculations needed. Moreover, this insight can also improve the understanding of material properties in general.
The calculation of the solid state part of a phase diagram is tremendously simplified by the assumption that lattice vibrations do not play a significant role in determining which configuration atoms will adopt. Yet, no formal justification of this approximation has ever been presented. In fact, through numerous experimental and theoretical investigations, researchers are now realizing that lattice vibrations may significantly affect the relative stability of two phases which differ only by the ordering of the chemical species on an otherwise identical lattice.
The effect of lattice vibrations is one of the last few elements that remain to be efficiently handled in order to quickly and accurately calculate the phase diagram of an alloy system. Our main research objectives are thus twofolds. (1) Improve our understanding of the factors which determine when lattice vibrations have a significant impact on the thermodynamics of an alloy. (2) Develop practical ways to include vibrational effects in phase diagram calculations.