Melt treatment and in-situ SiC in the Al-20Si alloy were investigated by smelting Al-20Si alloy in graphite crucible and taking phosphate as modifier.The results reveal that with increasing in holding time
grain size of primary phase is gradually refined
where holding time is 0
1
3
6min
grain sizes are 18
15
12
9μm
respectively.SiC is resulted from the reaction of C atom and hypereutectic Al-Si alloy.One part of generated SiC particle in solidification process act as heterogeneous nuclei of primary Si by agglomerating around Si colony
the other is dissolved into the primary Si phase and matrix.