Unidirectional solidification of aluminium-nickel eutectic alloy

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 mu m s(-1)) and different temperature gradients G (0 83-4 02 K mm(-1)) and also with a constant G (4 02K mm(-1)) and different V (8 32-483 25 mu m s(-1)) in the Bridgman type directional solidification furnace The eutectic spacings lambda have been measured from both transverse section (lambda(T)) and longitudinal section (lambda(L) lambda(m) and lambda(M)) of the specimens The undercooling values Delta T were obtained by using V and system parameters K(1) K(2) It was found that the values of lambda decreased while V and G were increasing The relationships between eutectic spacing lambda and solidification parameters G and V were obtained by linear regression analysis The dependence of eutectic spacings lambda (lambda(T) lambda(L) lambda(m) and lambda(M)) on undercooling (Delta T) were also analysed lambda(2) V Delta T lambda Delta TV(-0 5) and lambda(2)G values were determined by using lambda Delta T V and G values The results obtained in this work were compared with the Jackson Hunt eutectic theory and similar experimental works