Synergistically reinforced boron carbide ceramics by introduction of Fe and BN

Abstract Boron carbide (B 4 C)‐FeB ceramics and B 4 C‐FeB‐BN ceramics are prepared via hot pressing with B 4 C plus different contents of iron (Fe) and B 4 C 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 B 4 C ceramics is discussed. Results indicate that Fe can react with B 4 C to form FeB, and enhance the densification and mechanical property of B 4 C ceramics. 5 wt% Fe is the optimal addition amount. Fe and BN can synergistically reinforce B 4 C ceramics. The ceramics fabricated with B 4 C‐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 B 4 C or with B 4 C 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.