The semi-solid alloy slurry of Al-7 Si alloy was prepared by the internal cooling type mixing stirring method.The effects of different melt stirring initial temperature

ratio of internal cooling mixing block

stirring rate and sampling temperature on semi-solid microstructure and average grain size as well as the shape factor of the primaryα-Al in the Al-7 Si alloy were investigated.The mechanism of forming fine near-spheroids by internal cooling mixing methods was described.The results reveal that with the melt stirring initial temperature of 625℃

and ratio of mixing block of 5%

the stirring rate of 1 200 r/min and the sample temperature of 600 ℃

the semi-solid slurry with near-spherodized primaryα-Al can be obtained

where the average grain size and the shape factor reach 64.21μm and 0.649 0

respectively.