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

Abstract Dense and electrical discharge machinable B 4 C-TiB 2 -SiC triple-phase ceramic composites with high fracture toughness and high hardness were successfully fabricated via reactive hot-pressing sintering using B 4 C and nano-layered Ti 3 SiC 2 with different ratios as raw materials at a relatively low temperature of 1850 °C. The results showed that the mechanical properties of B 4 C-TiB 2 -SiC composite were remarkably enhanced than that of monolithic B 4 C ceramic. The micro-hardness, flexural strength, fracture toughness and compressive strength of B 4 C-TiB 2 -SiC composite prepared with B 4 C-30 vol% Ti 3 SiC 2 starting powder were 31.6 GPa, 492.3 MPa, 8.0 MPa · m 1/2 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 TiB 2 and SiC particles in the B 4 C matrix. Moreover, the composites exhibited significantly improved machinability than monolithic B 4 C, as evidenced by electrical discharge machining.