• Anisotropy of interfacial energy and dendrite morphology in Zn alloys. • Anisotropy coefficient a 0 6 in spherical harmonics is essential. • Anisotropy coefficients should be evaluated from growth morphology. Reliable data on solid–liquid interfacial properties for Zn alloys remain critically lacking. Time-resolved X-ray computed tomography at a large-scale synchrotron facility revealed dendritic morphologies growing in 14 directions, which cannot be adequately described solely by the interfacial energy anisotropy coefficients a 0 2 , a 0 4 , and a 6 6 based on spherical harmonics. To address this limitation, we introduce the coefficient a 0 6 . Phase-field simulations of equiaxed dendritic growth in a Zn–4 wt%Al alloy are performed while systematically varying the anisotropy coefficients. The results demonstrate that incorporating a 0 6 is essential to reproduce dendrite growth along 14 directions. Moreover, the relationship between equilibrium shapes and anisotropy coefficients shows that the effects of a 0 4 , a 0 6 , and a 6 6 are not readily evaluated from shapes experimentally obtained in pursuit of equilibrium, emphasizing the need to analyze growth morphologies to determine these coefficients accurately.
Yamamura et al. (Sun,) studied this question.