Macrosegregation mechanism of primary silicon phase in selective laser melting hypereutectic Al - High Si alloy

Macrosegregation of the primary silicon phase (proeutectic silicon) was observed in the selective laser melting in-situ processed Al-50Si alloys. Experimental results show that the Si-rich regions appear in the center and contour region. In contrast, the other region presents a Si-poor microstructure. The temperature field and fluid flow in the molten pool are the two key points for the segregation of the primary silicon phase. This work indicates that the macrosegregation is significantly influenced by the size and temperature of the molten pool, which is controlled by input energy density.