Effect of Sb and Al–3P Complex Modification on Solidified Microstructure and Mechanical Property of Hypereutectic Al–18Si Alloys

The present investigation involved the modified of Al–18Si alloys with the Sb and Al–3P at a temperature of 850°C. The findings indicated that the Sb can inhibit the formation of initial Si crystals in Al–18Si alloys, while simultaneously promoting the process of their growth. With a concentration of 0.3 wt %, the presence of Sb exhibited the most potent inhibitory impact on the precipitated phase of primary Si, resulting in the smallest average size and area percentage for it in Al–18Si alloys. Furthermore, there was an 11.4% enhancement in the tensile strength and a significant 190% increase in the elongation. The Al–3P and 0.3 wt % Sb complex modification can enhance the formation of primary Si crystals in Al–18Si alloys while preventing their growth. The 0.4 wt % Al–3P modified Al–18Si–0.3Sb alloys results in the smallest size of primary Si in the solidified microstructure of the alloys. The complex modification of Al–18Si alloys enhances their tensile strength by 13.8% when compared to Al–18Si–0.3Sb alloys.