The mechanism of the reactions between alumina and modifier strontium in molten A356 alloy have been investigated

by means of XRD and SEM.The results showed that there have been a series of reactions between them

forming the kind of compounds Sr-Al-O

which are water-soluble

and this led to the consumption of strontium.When adding strontium into the molten Al-Si alloys

the SrSi2 would form firstly

and then the Al2Si2Sr compound formed through ternary eutectic reaction

which appeared in the shape of both bulk and strip.The Al-Si-O compound was also found which laid over the Al2Si2Sr compound.