Evolution of eutectic spacing during unidirectional solidification of Al-Ni alloys

hypoeutectic al-ni alloys show a ductile phase α distributed with a β phase al3ni fragile where β serves as reinforcement of the structure of the material. the eutectic composition alloys obey the relationship: λ2.v = c, where λ is the eutectic spacing, v is a tip growth rate and c is a constant. the aim of this study is to establish correlations between λ and v for hypoeutectic al-1%, 3% and 5% ni alloys. unsteady-state upward directional solidification experiments were performed, as well as metallography, dissolution of the aluminum matrix and scanning electron microscopy (sem). the interphase spacing of the three al-ni alloys decreased with increasing tip growth rate, with a predominance of a rod-like morphology on intermetallic. it was observed that parameters such as tip growth rate, cooling rate and temperature gradient decreases as the solidification front advances. it was further observed that a single experimental law λ = 1.2 v-0, 5 illustrates the evolution of the interphase spacing for any examined alloy.