Date of Award
Doctor of Philosophy
In this thesis, we study dynamical aspects associated with (a) phase separation in binary mixtures, which involve their time evolution and time-dependent correlation behaviour, and (b) pattern formation in martensitic transformations. Using a Langevin model, we show for the first time how the predictions of scaling the dimensional arguments for two and three dimensional binary mixtures may be validated numerically within the context of a single model. In particular, we show how domain growth exponents result by an appropriate choice of the crossover lengths in the diffusive, viscous and inertial regimes. We also find that the small-wavenumber-scaling of the structure function is correlated with the velocity-velocity spectrum in fluids. We study the decay of the local autocorrelation and two-time correlation in both binary alloys and binary fluids. We show that the difference between theoretical predictions and numerical simulations for the decay exponent for conserved systems can be related to the sensitivity of the exponent to the amplitude of initial conditions. In simulating martensitic transformations in shape memory alloys, we show the formation of twin martensites and tweed precursors in corresponding regimes with a Langevin model. The Langevin model predicts a hierarchical structure near the habit plane, which provides an explanation of the shape memory mechanism.
Wu, Yanan, "Langevin Simulations Of First-order Phase Transitions In Fluids And Materials" (1996). Digitized Theses. 2630.