Synergistically reinforced boron carbide ceramics by introduction of Fe and BN

Boron carbide (B₄C)-FeB ceramics and B₄C-FeB-BN ceramics are prepared via hot pressing with B₄C plus different contents of iron (Fe) and B₄C plus 5 wt% Fe and different contents of boron nitride (BN), respectively. The phase composition, microstructure, and mechanical properties of the prepared ceramics are studied in detail. The synergistic effect of Fe and BN on hot-pressed B₄C ceramics is discussed. Results indicate that Fe can react with B₄C to form FeB, and enhance the densification and mechanical property of B₄C ceramics. 5 wt% Fe is the optimal addition amount. Fe and BN can synergistically reinforce B₄C ceramics. The ceramics fabricated with B₄C-5 wt% Fe-4 wt% BN have the optimal comprehensive performance, of which the relative density, hardness, flexural strength, and fracture toughness reach 98.5%, 32.74 GPa, 668.92 MPa, and 4.09 MPa·m^1/2, respectively, higher than those of the ceramics fabricated with B₄C or with B₄C plus Fe. The liquid formed by Fe during sintering enhances the dispersion of BN, which is beneficial to realizing the function of pinning grain boundary and pulling out. The toughening phenomena include intergranular and transgranular fracture, particle pulling out, and bridging.