Semi-solid slurry of aluminium alloy A356 was prepared by self-inoculation method（SIM）.The difference of microstructure of alloy prepared by semi-solid metal casting and traditional permanent mold casting was analyzed comparatively

and effects of holding time and temperature on water-quenched microstructure of A356semi-solid slurry were described.The results indicate that the uniform primary particles with non-dendrite structure in A356 aluminium alloy can be observed by semi-solid rheological casting with SIM.The shape factor of primary particles reaches or nearby 1

and average grain size is relatively fine with the slurry isothermally holding for 3min.Therefore

an ideal rheological microstructure can be obtained with the slurry holding for 3 min.The solid fraction directly depends on pouring temperature

where at high solid fraction（more than 50%）

serious mergence of primary particles can result in the structure worse.On the contrary

it is hard to get ideal feeding effect during semi-solid processing at low solid fraction（less than 15%）.The suitable holding temperature of semi-solid treatment for aluminium alloy A356 is in range of 600 ℃

6

10 ℃。