No abstract

B 4 C composites toughened by MoB 2 /Mo 2 B 5 -SiC interlocking structure were prepared via reactive hot pressing with B 4 C and MoSi 2 as raw materials. The phase composition, microstructure, and mechanical properties of the fabricated B 4 C composites were studied. The crack propagation and fracture surface were observed, and the toughening mechanism was analyzed. The results indicate that the interlocking structure of MoB 2 /Mo 2 B 5 -SiC is formed in the obtained B 4 C composites. The relative density, flexural strength, and fracture toughness of the B 4 C composites reach 99.3%, 480 MPa, and 5.2 MPa·m 1/2 , respectively, when the MoSi 2 content is 30 wt%.The hardness is 33 GPa when the MoSi 2 content is 20 wt%. The special laminar fracture of the interlocking structure of MoB 2 /Mo 2 B 5 -SiC elongates the crack extending path and thus consumes more energy of crack extension. The phenomena of crack bridging and branching and the special laminar fracture of the interlocking structure have a synergistic effect on promoting the overall fracture toughness. K E Y W O R D SB 4 C composites, hot pressing, interlocking structure, MoSi 2