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, λa*, λm*, λM*), were measured from both transverse section (λa) and longitudinal section (λa*, λm*, λM*) 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