Synergistic Enhancement of the Strength-Ductility for Stir Casting SiCp/2024Al Composites by Two-Step Deformation

The 10 μm 10 vol% SiC_p/2024Al composites sheet was successfully fabricated by semi-solid stir casting followed with two-step deformation (extrusion and rolling). The two-step thermal deformation solves the sheet rolling formability of the SiC_p/2024Al composites produced by stir casting. Compared with the SiC_p/2024Al composites prepared by traditional powder metallurgy, this paper innovatively studied the synergistic enhancement between CuAl₂ phase and SiC_p on the mechanical properties. The result shows that the two-step deformation can significantly improve the uniformity of the distribution of SiC_p and CuAl₂ phases. At the same time, the average size of the SiC_p and CuAl₂ phase decreases after the two-step deformation. During the hot extrusion, SiC_p has an obvious hindrance to the refinement of the CuAl₂ phase. Moreover, the SiC_p/2024Al composites sheet exhibits excellent yield strength (295 MPa), ultimate tensile strength (489 MPa), and elongation (10.42%). The performance improvement of SiC_p/2024Al after two-step thermal deformation is mainly attributed to the improved interface bonding strength of SiC_p-2024 Al matrix, the refined SiC_p and the more uniform distribution of SiC_p.

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