LAUSR

Abstract Traditionally, uniform distribution of nanoparticles in metal matrix is considered to show best strengthening effect. For many years, the natural agglomeration tendency of nanoparticles restricts the development of nanocomposite prepared by casting method gravely. In this work, to simultaneously improve strength and ductility of metal matrix, a new strategy of constructing threadiness array of TiC nanoparticles in 2024 Al alloy has been proposed. In-situ synthesized TiC nanoparticles of 1.5 wt% were introduced to 2024 melt using Al–14TiC master alloy. By solidification and subsequent hot extrusion processes, the TiC nanoparticles exhibit specific threadiness arrays in the 2024–1.5TiC nanocomposite. Compared with 2024 matrix, both strength and ductility of the 2024–1.5TiC have been improved evidently, with ultimate tensile strength and elongation increased from about 430 MPa and 9.8% to about 550 MPa and 15.5%. Since the TiC threadiness has an aspect ratio up to 36.6 on average, load bearing effect is regarded as a possible strengthening mechanism responsible for the strength improvement. In theory, it contributes to 55.2 MPa for the increase of yield stress of the 2024–1.5TiC. With respect to ductility, fine grains of α-Al matrix resulted from TiC nanoparticles provide the 2024–1.5TiC with uniform deformation capability. Besides, it is found that the TiC threadiness arrays delay crack initiation and propagation during tensile deformation, which maintains the matrix is elongated continuously until high ductility.