The Al-13.6Cu-6Si alloy was solidified under the different pressure of 2

4

5

6GPa

respectively with the help of cubic anvil press.The microstructure and phase constituent of the samples were examined by optical microscope

scanning electron microscope and X-ray diffraction.The relationship between pressure and microhardness were determinated by microhardness testing.The experimental results show that

the microstructure of the alloy solidified under the high pressure is composed ofα-Al

β-Si

andθ-Al2Cu phase

which is the same as those of the alloy solidified under the normal pressure.However

its microstructural morphology is changed significantly

where the coupled eutectic structure of the alloy solidified under normal pressure has transformed to the divorced eutectic structure with the alloy solidified under high pressure.With the increase of the solidification pressure

the volume fraction of theα-Al is increased

and the hardness of the alloy is increased to the maximum value at 5GPa.