In-situ reaction sintered ReB2-B4C composite by reactive spark plasma sintering

The high cost of ReB2 limits its application as a member of novel high-hardness materials, which can be alleviated by forming composites with cheap compound(s). In the present study, a dense ReB2-B4C composite was fabricated via in situ reactive sintering by spark plasma sintering with Re and B13C2 (Re:B = 1:20) as raw materials. The phase composition, microstructure, Vickers hardness, and fracture toughness of the obtained composite were characterized, and the reaction mechanism, crack propagation, and toughening mechanism were clarified. XRD, SEM, Raman, and XPS results revealed that the obtained composite is mainly composed of ReB(2 )and B4C phases, with a small amount of free B and graphite coexisted. Vickers hardness of 33.5 +/- 4.4 GPa under 0.49 N load and 24.6 +/- 1.5 GPa under 4.9 N load and fracture toughness of 5.02 +/- 0.37 MPa center dot m1/2 were observed for the obtained composite. The toughening mechanism of the obtained ReB2-B4C composite including crack deflection crack and cracking bridging was analyzed in detail.