Abstract
Aluminium-nickel of (99.99 %) high purity eutectic alloy was melted in a graphite crucible under vacuum atmosphere. The eutectic alloy was directionally solidified upward with a constant growth rate, V (8.32 μm/s) and different temperature gradients, G (0.83-4.02 K/mm) and also with a constant G (4.02 K/mm) and different V (8.32-483.25 μm/s) in the Bridgman type directional solidification furnace. The eutectic spacings, λ_i, have been measured from both transverse section λ_T) and longitudinal section (λ_L, λ_m and λ_M) of the specimens. The undercooling values ΔT were obtained by using V and system parameters K₁, K₂ It was found that the values of λ_i decreased while V and G were increasing. The relationships between eutectic spacing λ_i and solidification parameters G and V were obtained by linear regression analysis. The dependence of eutectic spacings λ_i λ_T, λ_L, λ_m and λ_M) on undercooling (ΔT) were also analysed. λ²V, ΔTλ, ΔTV^-0.5 and λ²G values were determined by using λ_i, ΔT, V, and G values. The results obtained in this work were compared with the Jackson-Hunt eutectic theory and similar experimental works.

Key words
Al-Ni alloys, eutectic growth, eutectic spacing, undercooling

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