Directional solidification of Al–Cu–Ag alloy

Al-Cu-Ag alloy was prepared in a graphite cru- cible under a vacuum atmosphere. The samples were direc- tionally solidified upwards under an argon atmosphere with different temperature gradients (G = 3.99-8.79 K/mm), at a constant growth rate (V = 8.30 µm/s), and with differ- ent growth rates (V = 1.83-498.25 µm/s), at a constant gradient (G = 8.79 K/mm) by using the Bridgman type directional solidification apparatus. The microstructure of Al-12.80-at.%-Cu-18.10-at.%-Ag alloy seems to be two fi- brous and one lamellar structure. The interlamellar spacings (λ) were measured from trans- verse sections of the samples. The dependence of interlamel- lar spacings (λ) on the temperature gradient (G) and the growth rate (V ) were determined by using linear regression analysis. According to these results it has been found that the value of λ decreases with the increase of values of G and V. The values of λ 2 V were also determined by using the measured values of λ and V. The experimental results were compared with two-phase growth from binary and ternary eutectic liquid.