Al-Si和Al-Si-Sc合金的界面能各向异性的研究

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

摘要:

平衡液滴法(Equilibrium shape measurement)是一种确定晶体-熔体界面能各向异性参数的有效方法。本文利用平衡液滴法测量单相固体中夹带的平衡液滴的形状,得到了Al-Si和Al-Si-Sc合金的界面能各向异性参数计算值。通过定向凝固方法制备Al-2wt.%Si和Al-2wt.%Si-0.2wt.%Sc合金杆状试样,使用光学显微镜表征Al-2wt.%Si和Al-2wt.%Si-0.2wt.%Sc合金内部液滴手工连续磨样抛光后多个二维截面形状,计算了二维界面能各向异性参数的大小。利用FIB(Focused ion beam)技术连续切割了Al-2wt.%Si合金内部液滴,并用Image-J软件重构液滴三维形状,获得了三维界面能各向异性参数值以及三维界面能分布和界面刚度的分布。在此基础上,讨论了平衡温度和Sc元素对界面能各向异性参数的影响。

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.