In-situ （Al3Zr+Al2O3）/Al particulate reinforced aluminum matrix composites was synthesized by direct melt reaction method in Al-Zr（CO3） system with the reinforced particulate size of 0.5

3

μm. The apparent viscosity of the composites melt during synthesized process was measured with rotary cylinder method. The results indicate that apparent viscosity via time curves of the composites with 5% particle volumetric fraction belongs to a parabolic one

and keeps a constant value of 0.75 Pas after 25 min and is two times higher than that of 0.24 Pas of pure aluminum

which is attributed to the uniform and dispersive distribution of micron particulate in composites. Melt apparent viscosity of the composites with 15% particulate volumetric fraction is increased with the increase of time

and the particulate aggregation can be observed in the microstructure.