Microstructure and tribological properties of TiC particle reinforced 2024 aluminum matrix nanocomposites fabricated by laser powder bed fusion

This study investigates the influence of TiC content (0–5.0 wt%) on microstructural evolution and tribological properties of TiC-reinforced 2024 aluminum matrix nanocomposites additively manufactured by laser powder bed fusion (LPBF), with a focus on the grain refinement effects and post-heat-treatment performance. Results reveal that TiC addition enables columnar-to-equiaxed grain transition, eliminates hot cracking, and increases density to 99.1 %. The grains are refined to an average grain size of approximately 1.6 μm by adding TiC. Following heat treatment, multi-scale strengthening phases (Al₁₈Ti₂Mg₃, L₁₂/D0₂₂-Al₃Ti, G.P. zones, θ'') form, enhancing hardness from 126.4 to 152.1 HV. The composite with 2.5 wt% TiC exhibits optimal wear resistance, achieving a 61 % reduction in wear rate compared to the unreinforced alloy, despite a moderate increase in friction coefficient. The excellent wear resistance is attributed to synergistic effects of enhanced load-bearing capacity and the suppression of adhesive wear. These findings highlight multifunctional roles of TiC in microstructural control and property enhancement of LPBF-processed composites, providing insights for aerospace applications like high-strength fuselage frames and wear-resistant bushings.