Enhanced mechanical properties of cBN-Al-Si3N4 composites by introducing diamond.

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]