Enhanced nucleation of primary silicon in Al–20Si (wt%) alloy inoculated with Al–10Si–2Fe master alloy

• A novel Al–10Si–2Fe master alloy refines the silicon phase in Al–20Si.
• The refining efficiency is dependent on holding time.
• β-Al5FeSi particles evolve into a kind of clusters and enhance silicon nucleation.
• These clusters evolve into iron-poor particles after enhancing silicon nucleation.

A novel kind of Al–10Si–2Fe master alloy containing β-Al5FeSi particles gives rise to an enhanced nucleation of primary silicon in Al–20Si alloy. Thermal analysis and TEM characterization were used to elucidate the inoculating mechanism. Inoculation reduces the nucleation and growth undercooling of primary silicon and introduces undetermined crystalline particles into silicon phase. Combined with the in-situ XRD patterns of Al–10Si–2Fe alloy, the added β-Al5FeSi particles are deduced to transform into a kind of clusters, instead of decomposing completely or staying stable. The transformed clusters and their aggregates enhance the nucleation of silicon phase and then evolve into the undetermined crystalline particles.