Modelling dendrite evolution under rapid solidification conditions

The evolution of a single dendrite is simulated by the cellular automaton ( CA) method, in which the influences of interface velocity on the solute partition coefficient ahead of the interface and liquidus slope are investigated under rapid solidification conditions. Furthermore, the kinetic undercooling ahead of the interface is also taken into account, which is neglected under normal solidification conditions. The simulated dendrite morphology is compared with that of the equilibrium conditions and it is shown that the interface easily loses stability around the dendritic tip causing more and more secondary dendrite arms to appear. In addition, the solute partition coefficient increases when the interface velocity increases, which leads to a decrease in solute microsegregation.