Composite refining alterant for casting aluminum-silicon alloy and application of composite refining alterant

The invention discloses a composite refining alterant for casting an aluminum-silicon alloy, which is characterized in that Al-10Sr, Al-10Y intermediate alloy and a titanium agent are used as the composite refining alterant, the adding proportion of Sr is 0.01-0.05% of the total mass of the aluminum alloy, the adding proportion of Y is 0.1-0.5% of the total mass of the aluminum alloy, and the adding proportion of Ti is 0.01-0.15% of the total mass of the aluminum alloy. The composite refining modifier treats an alloy melt, the modification effect is maintained for a long time, meanwhile, the air suction reaction caused by traditional Al-Sr modification is avoided, a heterogeneous nucleation core is more efficiently formed in the melt, alpha-Al grains are finer, eutectic Si is in a fiber shape or a coralline shape, and therefore the alloy performance is improved. And the microstructure of the cast aluminum-silicon alloy is obviously improved, and the mechanical property of the product is improved. 本发明公开了一种铸造铝硅