Densification and mechanical properties of pulsed electric current sintered B4C with in situ synthesized Al3BC obtained by the molten-salt method

The in situ generated ternary compound Al3BC shows good dispersion on the surfaces of B4C particles (10 ± 0.6 μm), obtained using the molten-salt method rather than the ball-milling method, which can form a conductive network in the pulse electric current sintering process to improve the sinterability of B4C. The sintering behaviour, microstructure and mechanical properties of compacts were investigated at different sintering temperatures and Al3BC contents. The study found that the relative density, elastic modulus, Vickers hardness, and fracture toughness of samples reached as high as 100%, 495 GPa, 37.0 GPa, and 6.32 MPa m1/2 at 1700 °C, respectively, when the content of Al3BC was 18 wt.%. The crack propagation mode can provide an explanation for the higher toughness than that of pure B4C (3.19 MPa m0.5). Additionally, the good dispersion of Al3BC in B4C was found to change the fracture mode from the single transgranular mode to a mixture of intergranular and transgranular modes. The compositions of the compacts were almost pure B4C.