Effect of in situ γ-Al2O3 particles on the microstructure of hypereutectic Al–20%Si alloy.

Highlights: [•] Aluminum ammonium sulfate (NH4Al(SO4)2) power can decomposed out γ-Al2O3 particles in high temperature Al–20%Si alloy melt. [•] In situ γ-Al2O3 particles can refine primary and eutectic Si phases of Al–20%Si alloy. [•] The refinement mechanisms are attributed to heterogeneous nucleation and restrict growth. [ABSTRACT FROM AUTHOR]