Study on anisotropy of crystal-melt interfacial energy for Al-Si and Al-Si-Sc alloys

Abstract:

The equilibrium shape measurement (ES) has been proved to be an effective method to determine the anisotropy of crystal-melt interfacial energy. In this paper, ES method is utilized to measure the shape of liquid droplets entrained in single-phase solid, and to calculate anisotropy parameters for Al-Si and Al-Si-Sc alloys. Rod-shaped Al-2wt.%Si and Al-2wt.%Si-0.2wt.%Sc alloy specimens are produced using the directional solidification process, followed by heat treatment and quenching. Specimens are sectioned normal to the <100> direction. Optical microscopy is used to characterize 2-D droplet shapes obtained by using sequential grinding for Al-2wt.%Si and Al-2wt.%Si-0.2wt.%Sc alloys, and then anisotropy parameters of interfacial energy were calculated. 3-D morphologies of droplets sliced by using focused ion beam (FIB) for Al-2wt.%Si alloy were reconstructed with Image-J software. Anisotropy parameters of interfacial energy were calculated and the 3-D interfacial energy and interfacial stiffness were plotted by using Matlab software. Effect of equilibrium temperature and Sc element on anisotropy parameters of interfacial energy were discussed for Al-Si alloys.