Effects of physical parameters on the cell-to-dendrite transition in directional solidification

A quantitative cellular automaton model is used to study the cell-to-dendrite transition (CDT) in directional solidification. We give a detailed description of the CDT by carefully examining the influence of the physical parameters, including: the Gibbs-Thomson coefficient Gamma, the solute diffusivity D-1, the solute partition coefficient k(0), and the liquidus slope m(1). It is found that most of the parameters agree with the Kurz and Fisher (KF) criterion, except for k(0). The intrinsic relations among the critical velocity V-cd, the cellular primary spacing lambda(c,max), and the critical spacing lambda(cd) are investigated.