Effects of Ni and Modificators on Microstructure of Hypoeutectic Al-Fe Alloy

The hypoeutectic Al-Fe alloy with 0.30 to 1.55wt% Fe was prepared by water-cooled rapid cooling copper mould.The effects of Fe,Ni and modificators on microstructure of hypoeutectic Al-Fe alloy were analyzed by using optical microscope,TEM and EDX.The results show that the eutectic compounds on the grain boundary increase gradually with the increasing of Fe and Ni contents;the number of secondary dendrite increases and interconnects into network structure;the granular Al9FeNi eutectic compound is lamellar in the Al matrix.When the Fe contents reach to 1.55% and Ni contents reach to 1.5%,the microstructure of alloy is lamellar,and the matrix contains lots of the coarse needle-like and needle plate-like primary phases.The modificator Al-Ti-B and Ce can refine obviously the coarse iron-rich primary phases and eliminate dendritic structure.But the refined effect of the Al-Ti-B on α-Al phase is not remarkable,while Ce can refine significantly the α-Al phase and the eutectic structure.