Effects of Computational Parameters on Solidification Structures Simulated with Phase-Field Method for a Ni-Cu Binary Alloy

摘要

In this study W was found to have strong effects on solidification structure of the binary alloy. Based 0.5 W_0, W_0 and 1.5W_0 base W_0, three conditions with free energy base W equal to 0.5 W_0, W_0 and 1.5W_0 respectively were computed. The results showed that the variation of energy base contributed a lot to the development of side branches of equiaxed dendrite structures, the lower W, the more developed side branches, the higher W, the more restrained side branches. Furthermore, the effects of boundary layer thickness δ on solidification structures were also studied. It is found that when the layer thickness δ is as small as △x/0.94, computational errors occurred at the base of the dendrite and when the layer thickness δ is as big as △x/0.54, some irreal phenomena, such as coarsened dendrite trunks and maladjusted side branches, could be caused. Further study on space step △x showed that bigger space steps made higher computational errors. It is given that the relationships among phase-field perturbation, space step and solidification structure.