5th International Conference on Advances in Solidification Processes (ICASP-5) 5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining (CSSCR-5)

The preferred growth direction of crystal in solidification of metallic materials is mainly determined by anisotropy of solid-liquid interface energy, g(n), where n represent the crystallographic orientation normal to the solid-liquid interface. The anisotropy of g(n) is described by anisotropy parameters e1 and e2 that characterize <100> and <110> growth, respectively. Effect of e1 has been considered in most of phase-field simulations for dendritic growth in metallic alloys which have a cubic crystal such as fcc and bcc, because the preferred growth orientation in cubic crystals has been supposed to be <100>. However, it was reported that the preferred growth direction of Al-Zn alloy, which has fcc structure, changes from <100> to <110> with an increase in Zn concentration [T. Haxhimali, A. Karma, F. Gonzales and M. Rappaz, Nat. Mater., 2006(5), 660.]. This phenomenon implies that anisotropy parameters depend on solute concentration. The morphological change of dendritic structures with transition in the growth direction of Al-Zn alloy was investigated in detail by phase-field simulations [J.A. Dantzig, P.D. Napoli, J. Friedli and M. Rappaz, Metall. Mater. Trans. A, 2013(44), 5532.] and several important findings were reported in the early work. A further investigation should be aimed at investigating effects of solidification conditions and type of alloy systems on the morphological change. Therefore, in this study, we conducted quantitative phase-field simulations to clarify the morphology of dendrites for different sets of e1 and e2 systematically. Also, effects of several factors such as degree of undercooling and temperature gradient in different alloy systems were investigated.