Scale-bridging phase-field simulations of microstructure responses on nucleation in metals and colloids

In the present studies we investigate the connection between atomistic simulation methods, i.e. molecular dynamics (MD) and phase-field crystal (PFC), to the mesoscopic phase-field methods (PFM). While the first describes the evolution of a system on the basis of motion equations of particles the second uses a Cahn–Hilliard type equation to described an atomic density field and the third grounds on the evolution of continuous local order parameter field. The first aim is to point out the ability of the mesoscopic phase-field method to make predictions of growth velocity at the nanoscopic length scale. Therefore the isothermal growth of a spherical crystalline cluster embedded in a melt is considered. We also show simulation techniques that enable to computationally bridge from the atomistic up to the mesoscopic scale. We use a PFM to simulate symmetric thermal dendrites started at an early stage of solidification related to nucleation. These techniques allow to simulate three dimensional dendrites from the state of nuclei (≈50?Å) converted from MD up to a size of some μm where ternary side-arms start to grow.