This study investigates laser-directed energy deposition (L-DED) fabricated 65   wt%TiC-10wt%B 4C-Ti composites on TC4 substrates, focusing on microstructure-property relationships and tribological performance under Si 3N 4 counterbody wear. The as-deposited composite exhibits α/β-Ti matrices reinforced with B 4C, TiB, TiB 2, and TiC phases, achieving bulk hardness of 786.5 HV 0.2 (vs. 450 HV 0.2 for TC4). Tribological analysis reveals distinct friction regimes: TiC-B 4C-Ti demonstrates a two-stage COF transition from initial climb-stabilization (0.671) to subsequent oscillatory attenuation (0.643) and eventual high-decline-rebound stabilization (0.628), while TC4 shows erratic fluctuations (0.377→0.582) with intensified late-stage wear. Wear mechanisms evolve from oxidation-dominated fatigue (microcracking, debris formation) to severe third-body abrasion in later intervals (4 th-6 th), linked to increased energy dissipation and debris coalescence. The composite achieves superior wear resistance (10 -14 m 3/(N·m)) compared to TC4 (10 -13 m 3/(N·m)), with linear energy-wear correlation in early stages transitioning to nonlinear behavior due to surface oxidation delamination (TiO/TiO 2/B 2O 3/TiBO 3). Tribochemical interactions in the Si 3N 4/TiC-B 4C-Ti system form protective transfer layers reducing substrate wear, while TC4 suffers from abrasive/adhesive wear with delamination. Worn surface analysis confirms dominant abrasive wear for both materials, with TiC-B 4C-Ti exhibiting enhanced tribochemical activity from B 4C phases. Debris ejection is more prevalent in the composite, evidenced by logarithmic wear volume relationships (lg(W disc)+lg(W Si3N4)=0.99 vs. 1.03 for substrate).