High toughness and electrical discharge machinable B4C-TiB2-SiC composites fabricated at low sintering temperature

Dense and electrical discharge machinable B4C-TiB2-SiC triple-phase ceramic composites with high fracture toughness and high hardness were successfully fabricated via reactive hot-pressing sintering using B4C and nano-layered Ti3SiC2 with different ratios as raw materials at a relatively low temperature of 1850 °C. The results showed that the mechanical properties of B4C-TiB2-SiC composite were remarkably enhanced than that of monolithic B4C ceramic. The micro-hardness, flexural strength, fracture toughness and compressive strength of B4C-TiB2-SiC composite prepared with B4C-30 vol% Ti3SiC2 starting powder were 31.6 GPa, 492.3 MPa, 8.0 MPa·m1/2 and 2727 MPa, respectively. High hardness was attributed to the low open-porosity and grain refinement, while the high toughness was mainly ascribed to the crack deflection due to the dispersed TiB2 and SiC particles in the B4C matrix. Moreover, the composites exhibited significantly improved machinability than monolithic B4C, as evidenced by electrical discharge machining.