Precipitation of (Al,Si)3Sc in an Al-Sc-Si alloy

Three-dimensional atom probe has been applied to investigate the solubility of Si in Al3SC in an Al-0.16Sc-0.05Si alloy. It was found that L1(2)-structured Si-containing Al3Sc precipitates formed after the alloy was aged at 300 degrees C. Results of first-principles calculation indicated that Si atoms tend to substitute Al sites in Al3Sc, and thus the precipitates can be represented as (Al,Si)(3)Sc. The (Al,Si)(3)SC was found to have a dramatic precipitation-strengthening effect in the cast alloy. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.