Journal of Crystal Growth, Vol.334, No.1, 170-176, 2011
Numerical modeling of crystal growth of a nickel-based superalloy with applied direct current
A cellular automaton-finite difference (CA-FD) model is developed to simulate crystal growth with applied direct current (DC) in this study. The simulated dendrite growth is controlled by the CA rules that involved the effects of the supercooling, interfacial curvature and crystal anisotropy. The electric current distribution, the temperature field and the electromagnetic flow caused by the Lorentz force are solved by the FD calculation. The directional solidification of a model nickel-based superalloy with DC field is simulated. The results show that Joule heat brought by electric current delays the dendrite growth and changes the primary dendrite arm spacing (PDAS). Excessive Joule heat will completely stop the crystal growth. The maximum allowable current intensity increases with the cooling efficiency of directional solidification. It is found that the dendrites growing with the DC field have a self-adjustment ability to achieve flat S/L interface in macroscale during directional solidification. The electromagnetic flow induced by the DC field may theoretically accelerate the dendrite growth, but usually the influence is negligible for the directional solidification of the superalloy. (C) 2011 Elsevier B.V. All rights reserved.