Spheroidization of Si in Al–12.6wt.%Si at eutectic temperature and its tensile properties

The morphology of Si affects significantly the mechanical properties of eutectic Al–Si alloy. In this letter, we report a novel method for the spheroidization of Si in eutectic Al–Si alloy. The results show that Si in eutectic Al–Si alloy could be spheroidized after annealing at eutectic temperature for 3 h. Si phase in the alloy exists in the form of ellipsoidal particles without faceted edges. The surface shape factor of Si phase is 0.8 and the average size of Si particles is only 3.3 µm. Compared with cast eutectic Al–Si alloy, the tensile strength and the hardness of the annealed alloy are decreased by 8.2% and 8.6%, respectively, but its elongation is increased by 79.4%. The fracture mode of Al–12.6%Si alloy annealed at 577 °C for 3 h belongs to ductile fracture.