Semi-solid A390 alloy was prepared by near-liquidus process. The microstructure evolution of A390 alloy with varied holding temperature and time was observed with the alloy melt held around the liquidus temperature. The results show that with the holding temperature decreased from 695℃ to 650 ℃

the α -Al phase in the microstructure of the alloy is transformed gradually from dendrite to rosette and then into spherical shape

and the primary Si is converted into refined particle. The uniform refined primary Si particle and nearly spherical α -Al can be obtained in the microstructure of A390 alloy with holding at 635

6

50 ℃ for 40

5

5 min. It is found that with increasing in cooling rate

the primary Si and α phase in the microstructure of the alloy become more refine and spherical

respectively.