Numerical Modeling of Deflected Columnar Dendritic Grains Solidified in a Flowing Melt and Its Experimental Verification

A two-dimensional, coupled, cellular automaton-continuum model was developed to model the evolution of solidification grain structures and the deflection behavior of the columnar dendritic grains solidified in a flowing melt. Al-Cu alloys were solidified on an inclined Cu chill in order to investigate the deflection behavior of columnar grains. The growth velocity of a dendrite was determined by the KGT (Kurz-Giovanola-Trivedi) model based on the calculated temperature and solute profiles around a dendrite tip during solidification. The deflection behavior of the growing grains in a flowing melt was studied by the macroscopic observation of the solidified shell on the inclined Cu chill plate, and the interpretation of this phenomenon was made with the aid of numerical calculation, including Cu solute redistribution and velocity vector profile around dendrite tips during solidification, with various solidification parameters. Effects of flow velocity and solute content on the deflection angle of the columnar grains were investigated through experiments, and the results were compared with the numerical simulations.