DYNAMICS OF PHASE-SEPARATION

A new framework is developed for a treatment of the unmixing of an alloy or another system undergoing a phase transition after a quench into the coexistence region. Expanding around a suitably chosen reference equilibrium state new order parameter fields are introduced by a regrouping of diagrams. In a path integral representation the action of the new fields is constructed in a renormalized form and calculated by ε expansion in d=4-ε dimensions. As a first application the timedependence of the structure factor is computed using a simple factorization. It is found that unmixing takes place in the whole coexistence régime with a lifetime of metastable states which diverges at the coexistence curve and with no sharp boundary between the spinodale and nucleation régime. © 1979 Springer-Verlag.