Abstract: The evolution of the morphology of eutectic Si in the DC casting Al127Si07Mg ingot with 110mm diameter during the salt bath heat treatment at 485℃ was studied by means of optical microscope(OM)， laser scan confocal microscope(LSCM) and scanning electron microscope(SEM).The results showed that by OM the section morphology of the eutectic Si in the ingot of DC casting Al127Si07Mg alloy was the mixture of spot and strip，but its 3D morphology was coral like structure. The corallike Si coarsened when the semicontinuous casting ingot was in the early stage of the reheating and holding treatment， furthermore， some of the long rodlike eutectic Si changed its morphology into the continued gourdlike shape which then broke up into granules getting coarsening and spheroidization afterwards， when the holding time of the heat treatment was prolonged The diameter of the eutectic Si particle and the holding time were in accordance with a power of 229 ~ 267 relationship during heating and holding the ingot at 485℃.

Key words: AlSi alloy, DC casting, eutectic Si, spheroidization, corallike shape