The purpose of this study was to investigate the effect of carbon nanotube addition on the microstructure and mechanical properties of Al–Cu–Mg alloy composites. By analyzing the XRD results, it was deduced that the extruded and heat-treated composites, after the addition of CNTs, were preferentially grown on the (220) crystal plane. In addition, the distribution of carbon nanotubes at α-Al grain boundaries was observed by SEM and TEM. The incorporation of carbon nanotubes leads to an increase in the degree of recrystallization in the composite. It is worth noting that according to the study of the four strengthening mechanisms of dislocation strengthening, grain refinement strengthening, load transfer strengthening, and second stage strengthening, when the carbon nanotube content is 1.5 wt.%, the tensile strength (480.4 MPa) and yield strength (456.68 MPa) are significantly improved.

In this study, SiCp/A357 composites containing 10% SiCp by mass were successfully fabricated using the semi-solid stir casting technique. The investigation focused on the microstructure, interfacial characteristics, and mechanical properties of the SiCp/A357 composites. The experimental findings indicated uniform distribution of SiCp within the matrix, with minimal interfacial reaction at the matrix and SiCp interface. Additionally, the interfacial bonding between SiCp and the matrix was found to be highly robust. The composites achieved an ultimate tensile strength of 233.4 MPa and an elongation of 7.67% prior to heat treatment. Following T6 heat treatment, the tensile strength showed significant improvement, reaching 431.9MPa, while the elongation decreased to 5.7%. The orientation relationship between the matrix and reinforcement was investigated, and first-principles calculations were employed to analyse the interfacial bonding between the reinforcement and the matrix. The simulations confirmed effective bonding, which consistent with the experimental observations.