Microstructures and mechanical properties of graphene platelets-reinforced spark plasma sintered tantalum diboride-silicon carbide composites

Graphene nanoplates reinforcement (GNPs) TaB₂-SiC composites were fabricated with Spark Plazma sintering (SPS) at 1850 °C with a-uniaxial pressure of 50 MPa and 10 min dwell time. Systematic investigation on the effect of GNP amount ofdensification, microstructural and mechanical properties (microhardness and fracture toughness) of the composites were presented. Density and hardness of composites decreased with the addition of GNP, while ∼35% increase of fracture toughness value was obtained with GNP addition. The microstructural evaluation indicated that overlapped and agglomerated GNPs increased with an increasing amount of GNP in the composites and caused to decrease of density and hardness. On the other hand, GNP was retained in the composite form even with high process temperature (1850 °C) and cause toughening of composites with changing the fracture mode from transgranular to transgranular/intergranular fracture. GNP pull out, crack branching, crack bridging and crack deflection were observed as main toughening mechanisms. (paper)