Microstructure and mechanical properties at both room and high temperature of in-situ TiC reinforced Al-4.5Cu matrix nanocomposite

Al-4.5Cu-xTiC (x = 0, 0.5, 1 and 1.5) alloys reinforced by in-situ synthesized TiC nanoparticles have been prepared by casting method in this work. It shows that the size of the synthesized TiC nanoparticles range mainly from about 30 to 90 nm. In the Al-4.5Cu-0.5TiC, the TiC distributes in matrix uniformly, and with the content increasing to 1.5%, some TiC was gathered along alpha-Al grain boundary. By TEM observation, the interface between TiC and alpha-Al is clean and well-bonded in atomic scale. Mechanical property tests show that both strength and ductility of the alloys at room and high temperature (350 degrees C) have been improved by the TiC nanoparticles. It was found that both the dispersed and gathered TiC contribute to the strength at high temperature, but only the dispersed TiC strengthen the alloy at room temperature effectively. It is suggested that TiC nanoparticles strengthen the alloys mainly via increasing dislocation density and impeding dislocation motion in matrix, and toughen the alloys mainly by grain refinement, which brings about uniform deformation and decreases the possibility for crack nucleation and propagation during loading. (C) 2018 Elsevier B.V. All rights reserved.