Enhanced mechanical properties of a novel heat resistant Al-based composite reinforced by the combination of nano-aluminides and submicron TiN particles

Abstract

A novel heat resistant aluminum matrix composite reinforced by the combination of nano-aluminides (Al4C3, AlN) and submicron TiN particles was fabricated by liquid-solid reaction method and the following extrusion process. The SEM and HRTEM characterization showed that the aluminides and TiN particles with the mean size of smaller than 50 nm and 300 nm are uniformly distributed in the Al matrix with a well atomic interface bonding structure. Due to the existence of the reinforcing particles in the matrix, continuous dynamic recrystallization of α-Al grains occurred in the matrix during the extrusion process and an ultra-fine grained structure was formed with an average size of about 0.65 μm. The novel composites exhibit an excellent tensile strength both at room temperature(RT) and high temperature(350 °C, HT), which can reach up to 325 MPa and 151 MPa, respectively, while maintaining a moderate tensile ductility, 12% and 7% at RT and HT. The strengthening mechanisms were also analyzed in detail based on the crucial roles of the dispersive reinforcement particles and theoretically calculation.