Tailoring microstructure and mechanical properties of B4C–TiB2 composites by controlled introduction of Fe–Cr debris via ball milling

B 4 C–TiB 2 composites with enhanced mechanical properties were fabricated by a hydrolysis-based coating process, followed by ball milling with stainless-steel media, and consolidated by reactive hot pressing. Milling with 9Cr18 stainless-steel balls introduced Fe–Cr debris, which generated a liquid phase during sintering, promoting the formation of coarse, plate-like (Ti,Cr)B 2 solid-solution grains and a newly formed FeB phase. The optimal flexural strength of 745.7 ± 37 MPa is achieved, attributed to solid-solution strengthening and improved microstructural homogeneity. Meanwhile, the highest fracture toughness and Vickers hardness of 5.40 ± 0.28 MPa m 1/2 and 37.4 ± 1.3 GPa are achieved when the milling time is prolonged to 3 h, representing a 27% and 9.67% improvement, respectively, compared to the composites without ball-milling treatment. These results demonstrate that controlled introduction of Fe–Cr debris by stainless-steel ball milling enables simultaneous enhancement of flexural strength, fracture toughness, and hardness in B 4 C–TiB 2 composites through liquid-phase sintering.