Spinodal decomposition of fine-grained binary alloys: A Monte-Carlo simulation

The kinetics of spinodal decomposition of binary alloys in case of finite g rain size and slow grain growth is studied by applying the Monte-Carlo meth od where a coupled algorithm of the spin-exchange Ising model and Q-state P otts model operates. The anisotropic energy of grain boundaries is incorpor ated by imposing a Potts spin lattice on the Ising crystal. We simulate the phase separation where the grain size is comparable with the spinodal leng th on the order of magnitude. It is revealed that the grain boundaries of l ow excess energy as rapid channel enhance the solute diffusion, whereas tho se boundaries of high excess energy hinder the solute diffusion. Depending on the system supersaturation, phase aggregation preferred at the grain bou ndaries is demonstrated. The spinodal kinetics is modulated by the grain gr owth so that the Lifshitz-Slyozov-Wagner law may no longer be applicable in spite of the scaling law roughly holds in present system. (C) 2000 Kluwer Academic Publishers.