Multi-scaling properties of phase segregation in quenched binary fluids

The phase separation process in two-dimensional binary fluid systems is investigated using molecular dynamics for almost 20 000 particles. Previous works from the same authors have shown that the late-stage coarsening regime at critical volume fractions is described by power laws whose exponents are dependent on particle–particle interactions and on temperature in a non-universal way. At the low-temperature region, however, the emergence of a three-phase regime of percolating domains with atoms of type-A, type-B and voids, invalidates the single-length scale invariance. We argue in terms of a multiple-length scale analysis. In particular, for the case we studied with symmetric molecular pair potentials we propose two divergent length scales to characterize the dynamic process: one associated to the average size of equal-atom domains and the other related to the average size of undistinguishable-atom domains. Two different growth exponents can be inferred in such a case but the system does not exhibit scale invariance.