Experimental determination of solid-liquid interfacial free energy anisotropy in Al-Zn via equilibrium droplet method

Abstract

The increasing Zn content causes dendrite orientation transition during solidification of Al-Zn alloys, which is supposed to be related to the change of solid-liquid interfacial energy anisotropy. In this paper, experimental measurements of the interfacial energy anisotropy were performed in Al-17, 30 and 75wt.%Zn alloys with equilibrium droplet method. Droplets shape in relation to crystal orientation and droplets morphology are obtained by Electron Back-Scatter Diffraction and X-ray Computed Tomography, respectively. The result indicates that anisotropic parameters ε1 and ε2 both decreases with increasing Zn concentration and the directions of maximum interfacial energy transform from 〈100〉 directions in Al-17wt.%Zn and Al-30wt.%Zn to 〈110〉 directions in Al-75wt.%Zn. In addition, the Wulff plot and normalized interfacial stiffness are quantified and compared with the corresponding Al-Zn dendrites orientation selection.