High-temperature mechanical properties of 2024 Al matrix nanocomposite reinforced by TiC network architecture

In this work, 2024 Al matrix composite reinforced by 1.5 wt% in-situ synthesized TiC nanoparticles has been fabricated by casting method. It was found that TiC nanoparticles were distributed along alpha-Al grain boundaries, which formed network architecture, and average cell size of the TiC network was 48 mu m. The 2024-1.5TiC nanocomposite exhibited enhanced mechanical properties compared to 2024 base alloy. The ultimate tensile strength at 350 degrees C was increased from 105 MPa to 151 MPa, with elongation reasonably decreasing from 9.5% to 7.1%. It was observed that the presence of the TiC network transformed deformation behavior of alpha-Al matrix from local deformation to overall deformation during tensile test at high temperature. This enhanced strength of the 2024-1.5TiC, which contributed to similar to 84% increase in yield strength theoretically. Accordingly, a new strengthening mechanism named as constraint strengthening has been put forward in this paper. This principle was supposed to be applicable for microstructure design of other alloys and composites. In addition, the circle network was shifted to be oval one during deformation, but the interconnectivity has not been broken. This produced reasonably high ductility for the 2024-1.5TiC nanocomposite.