Effects of Sr addition on the microstructure and mechanical properties of the as-cast Al-7Si-Mg alloy have been investigated.The results indicate that the grain size is increased with the addition of Sr element

and the morphology of primary dendrite is transformed to columnar structure.With the increase of Sr addition

the morphology of eutectic Si is changed from coarse planar or acicular structure to fine fibrous one.Meanwhile

the Al-Si-Sr ternary phases can be observed in the alloy with gathered along the interface of eutectic and primary α-Al with 0.06% Sr.With 0.04% Sr addition

the tensile strength and elongation of the as-cast Al-7Si-Mg alloy reach a desirable value

increased by 8.4 MPa and by 68.4%

respectively

compared with those of the unmodified alloy.