LATE-STAGE COARSENING DYNAMICS IN PHASE-SEPARATING SYSTEMS - SIMULATION RESULTS

Simulations of diffusional interactions among precipitate particles wi th a given instantaneous size distribution and volume fraction are ref erred to as snapshot simulations. Dynamic (time-dependent) and snapsho t simulations of large ensembles of coarsening particles with monopola r and dipolar interactions are presented. The snapshot simulations sho w that the deviation of coarsening rates from that of the infinite dil ution limit of TLS varies as 3 root V-upsilon or root V-upsilon (Debye screening) depending on the range of volume fraction and number of pa rticles in the system. Dynamic simulation results of the same system c onfirm the cubic growth law of particles showing that they are in the asymptotic regime. The deviation of coarsening rates from TLS from dyn amic simulations is larger than that predicted by the snapshot simulat ions at V-upsilon = 0.10 and higher. The results of the snapshot and d ynamic simulations however agree at volume fractions less than or equa l to 0.01. Structure factor calculations indicate that the scaled stru cture factor S(q) similar to q(-4) (Pored's law) at large values of wa ve number q, consistent with the presence of sharp interfaces between the droplet and matrix phases. (C) 1997 Elsevier Science S.A.