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 L12-structured Si-containing Al3Sc precipitates formed after the alloy was aged at 300 °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)3Sc. The (Al,Si)3Sc was found to have a dramatic precipitation-strengthening effect in the cast alloy.