Preparation of B4C composites toughened by MoB2/Mo2B5‐SiC interlocking structure via reactive hot pressing

Abstract

AbstractB4C composites toughened by MoB2/Mo2B5‐SiC interlocking structure were prepared via reactive hot pressing with B4C and MoSi2 as raw materials. The phase composition, microstructure, and mechanical properties of the fabricated B4C 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 MoB2/Mo2B5‐SiC is formed in the obtained B4C composites. The relative density, flexural strength, and fracture toughness of the B4C composites reach 99.3%, 480 MPa, and 5.2 MPa·m1/2, respectively, when the MoSi2 content is 30 wt%. The hardness is 33 GPa when the MoSi2 content is 20 wt%. The special laminar fracture of the interlocking structure of MoB2/Mo2B5‐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.