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Cubic boron nitride (cBN) matrix composites were fabricated by introducing submicron diamond under high pressure and high temperature (5.5 GPa, 1500 °C). A systematic evaluation of the effects of diamond content on phase composition, microstructure, and mechanical properties of the composites was conducted. We found that diamond has a significant effect on improving the mechanical properties of the composite. The introduction of a small amount of submicron diamond is beneficial to obtain a dense microstructure. The hardness of the composite increased monotonously with increasing diamond content, and the maximum value reached 54.92 GPa. With diamond content of 4 wt%, flexural strength, relative density, and fracture toughness of the composite all reached the maximum value, which was 726.27 MPa, 99.21%, and 7.46 MPa·m1/2, respectively. [Display omitted] • The fracture mechanism of cBN composites is studied. • The influence of diamond addition on the phase composition is studied. • 4 wt% diamond can significantly improve the mechanical properties of the composite. [ABSTRACT FROM AUTHOR]

In this research, the cBN composites were fabricated with SiC p -Al as ceramic-metal binder and SiC whiskers (SiC w) as reinforcement via high-temperature and high-pressure (HTHP) sintering. The influences of SiC w on the morphology and mechanical behaviors of PcBN-SiC w composites were systematically evaluated. The results manifested that the samples doped SiC w not only obtained the compact microstructure but also presented better mechanical properties. When the content of SiC w equaled to 15 wt%, the highest fracture toughness reached 7.38 MPa m1/2. Additionally, the flexural strength reached an optimum value of 695.85 MPa with 10 wt% SiC w. In comparison to the composites without SiC w , the fracture toughness and flexural strength increased 41.9% and 23.5%, respectively. The improvements could be ascribed to the strengthening and toughing effects of SiC w including the pull out, bridging and crack deflection. • SiC whiskers were used to reinforce the cBN-SiC p -Al composites. • The mechanical properties of the PcBN-SiC w composites were significantly improved. • SiC whiskers pullout, bridging and creak deflection caused the increase of toughness. • The PcBN-SiC w composites were sintered by high temperature and high pressure. [ABSTRACT FROM AUTHOR]