Microstructure, Mechanical, and Tribological Properties of TiC- and Ni-Reinforced AA6061 Matrix Composite Fabricated Through Stir Casting

Aluminum matrix composites incorporating titanium carbide (TiC) and nickel (Ni) were fabricated through the ultrasonic-assisted stir-casting technique. Micrographs revealed the uniform dispersion of TiC particles within the matrix, while Ni reacted with aluminum, forming the intermetallic compound Al3Ni, dispersed along the grain boundaries. The incorporation of TiC and Ni resulted in a considerable decrease in grain size from similar to 130 to similar to 49 mu m. Notably, the incorporation of 3 wt% TiC and 6 wt% Ni (sample S(3,6)) exhibited a substantial increase in yield strength (YS), ultimate tensile strength (UTS), and hardness by 51.11%, 32.57%, and 46.96%, respectively, compared to the unreinforced sample S(0,0). The observed improvements in these properties can be ascribed to a mix of factors, including grain refinement, Al3Ni precipitate hardening, and dispersion hardening facilitated by the TiC particles. The increase in reinforcement weight percentage results in a decrease in the wear rate of reinforced composites, while wear rates for these composites exhibit a linear increase with a change in load from 10 to 20 N.