The effects of different La additions on structure and cooling curve of Sr modified Al-9 Si-Cu alloy were investigated.The results show that with the increase of addition of La（0～0.8%）

the size of primaryα-Al of0.02 Sr modified Al-9 Si-Cu alloy is decreased

and the minimum growth temperature T

min-α

and maximum growth temperature T

G-α

of primaryα-Al are increased.A small amount of La addition（0.1%～0.2%）can enhance significantly the modification effect of eutectic Si

decrease eutectic minimum temperature T

min-si

and maximum temperature T

G-si

and increase eutectic recalescence temperature(ΔT

R-Si

).However

with the addition of a higher amount of La（0.4%～0.8%）

eutectic silicon modification effect is deteriorated

while T

min-si

、T

G-si

andΔT

R-Si

are decreased.It is found thatΔTR-Sihas a good function with the eutectic silicon modification effect

and with the increase of the ΔT

R-Si

the modification effect is improved.