The effects of Y on primary α-Al and precipitation of hypoeutectic Al-Si alloy

Abstract

Under sand casting conditions, the effects of yttrium (Y) on the primary α-Al and precipitation of A357 alloy were investigated. The results showed that with Y addition, the primary α-Al nucleation was more difficult, and the Tliquidus-Tsolidus decreased. Meanwhile, the number of the dendritic primary α-Al grains increased, the primary dendrite arms became longer and narrower, and the secondary dendrites had longer arms and smaller arm spacing. Some other elements had the same phenomenon, like Si, Sr, etc. As for precipitation, with Y addition, the number of β″ decreased. Y did not affect the β″ habit plane and did not change the types or produce new precipitation.