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

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