Eutectic growth of unidirectionally solidified bismuth–cadmium alloy

Bismuth (Bi)–Cadmium (Cd) eutectic alloy was melted in a graphite crucible under vacuum atmosphere. This alloy was directionally solidified upward with a constant growth rate, V (8.33 μm/s), and different temperature gradient ranges, G (1.93–4.74 K/mm), and also with a constant G (4.74 K/mm), and different V (8.33–167.32 μm/s) in the Bridgman type directional solidification furnace. The lamellar spacings λi (λa, image, image, image), were measured from both transverse section (λa) and longitudinal section (image, image, image) of the specimens. The variations of λi with respect to G and V were determined by using linear regression analysis. The dependence of lamellar spacings λi on undercooling (ΔT) was also analysed. The variations of ΔT with G at constant V and with V at constant G were investigated. According to these results, it has been found that λi decreases with increasing values of G and V. Also ΔT increases with increasing V for a constant G and with increasing G for a given V, respectively. λ2V, ΔTλ, ΔTV−0.5 and λ2G values were determined by using λi, ΔT, V and G values. The results obtained in this work have been compared with the Jackson–Hunt eutectic theory and the similar experimental results