THE MASTER EQUATION APPROACH TO CONFIGURATIONAL KINETICS OF ALLOYS VIA THE VACANCY EXCHANGE MECHANISM - GENERAL RELATIONS AND FEATURES OF MICROSTRUCTURAL EVOLUTION

The earlier-suggested generalized Gibbs distribution approach to the c onfigurational kinetics of non-equilibrium alloys is extended to the c ase of many-component alloys and the realistic vacancy-mediated atomic exchange mechanism is incorporated. Exact and approximate equations f or the temporal evolution of atomic distributions as well as for the f ree energy of a non-equilibrium alloy are presented. It is shown that the evolution of the main alloy component distribution for the nearest -neighbour vacancy exchange model can usually be described in terms of an equivalent direct exchange model. This conclusion is illustrated w ith the computer simulation of decomposition and ordering via the vaca ncy exchange mechanism for a two-dimensional alloy model. The simulati on also reveals the localized ordering phenomenon at very early stages of ordering, in agreement with previous experiments and Monte Carlo s imulation, but with no interfacial vacancy trapping which was suggeste d in previous works in order to explain this phenomenon.