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 ~ 130 to ~ 49 µm. 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.