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Using the phase-field crystal model, we address the evolution of complex solidification morphologies and the solid-liquid transformation kinetics on the atomistic scale. In single component systems, we observe a diffusion controlled growth mechanism at low supersaturations, which replaced by an interface controlled mechanism at high supersaturations, a behavior reminiscent to that seen in colloidal systems. We present a morphology map that shows the different growth mechanisms resulting essentially different morfologies. The growth kinetics and also the interface properties of the different growth modes are discussed. Next, we use a recent model of Elder et al. (2007) to investigate morphological transitions in a binary system of ~1.6 million atoms, and determine morphological aspects of dendritic solidification including the variation of tip radius and velocity as a function of time. Finally, we address transformation kinetics of polycrystalline solidification in single component and binary systems, and compare the respective behaviors of the Avrami-Kolmogorov exponent describing the time evolution of freezing. |
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