The microstructure of eutectic ZL108 aluminum alloy prepared by single roller rotating-quenching method was observed by DSC（differential scanning calorimetry）

X-ray diffraction （XRD） and transmission electron microscope（TEM）. The results indicate that the only presence of Al diffraction peak can be observed in the diffraction spectrum of the rapidly solidified alloy

exhibiting the samller lattice constant compared with the conventional alloy. And the rapidly solidified alloy has more an exothermic peak than the conventional alloy in the DSC curves of heat flow-temperature before melting. TEM observation reveals that there exists hypoeutectic solidified structure without developed dendrite in the rapidly solidified alloy

which is composed of micron grain and eutectic area in which nanometer Si particle exists. It can be concluded that the alloy elements such as Si has almost fully dissolved into Al solid solution

resulting in the enlargement of dissolvability and the movement towards right of eutectic point

meanwhile

the microstructure of the rapidly solidified alloy is greatly superior to that of conventional alloy.