Abstract:The 2024 nanocomposite reinforced with Al 2 O 3 nanoparticles was fabricated by the ultrasonic assisted semisolid stirring (UASS) method and rheoformed into a cylinder component. Microstructure, mechanical properties, and wear behavior of the rheoformed composite components were investigated. The results showed that the composite components with complete filling status and a good surface were rheoformed successfully. The deformation of semisolid slurries was mainly dominated by flow of liquid incorporating solid grains (FLS), sliding between solid grains (SSG), and plastic deformation of solid grains (PDS). Mechanical properties of the rheoformed composite components were influenced by stirring temperature, stirring time, and volume fraction of Al 2 O 3 nanoparticles. The optimal ultimate tensile strength (UTS) of 358 MPa and YS of 245 MPa were obtained at the bottom of the rheoformed composite components after a 25-min stirring of composite semisolid slurry with 5% Al 2 O 3 nanoparticles at 620 • C. Enhancement of mechanical properties was attributed to high density dislocations and dislocation tangles and uniform dispersed Al 2 O 3 nanoparticles in the aluminum matrix. Natural ageing led to the occurrence of needle-like Al 2 CuMg phase and short-rod-like Al 2 Cu phase. UTS of 417 MPa and YS of 328 MPa of the rheoformed composite components were achieved after T6 heat treatment. Improvement of mechanical properties is due to the more precipitated needle-like Al 2 CuMg phase and short-rod-like Al 2 Cu phase. Wear resistance of the rheoformed composite components was higher than that of the rheoformed matrix component. Wear resistance of the rheoformed composite component increased with an increase in Al 2 O 3 nanoparticles from 1% to 7%. A slight decrease in wear rate resulted from 10% Al 2 O 3 nanoparticles due to greater agglomeration of Al 2 O 3 nanoparticles. A combination mechanism of adhesion and delamination was determined according to worn surface morphology.