EFFECTS OF ENCOUNTERS ON PHASE-SEPARATION DYNAMICS FROM DIFFUSION-CONTROLLED GROWTH TO COARSENING

We investigate the dynamics of phase separations in quenched binary mi xtures, such as binary alloys and polymer blends with low mobilities, at higher volume fractions. Computer simulations are performed using s imple model equations in the presence of encounters of droplets. Four characteristic stages with three crossovers, including dynamical scali ng behavior and temporal power laws, are found beyond a volume fractio n of approximately 0.14, where each crossover is attributed to a trans ition from one growth mechanism to the other. The encounter effect is thus shown to strongly influence a transition from the diffusion-contr olled (t(1/2)) Stage to the coarsening (t(1/3)) stage. A simple analyt ical argument for the simulation results is also presented.