Effect of Ti₂AlC/Al Binder Content on the Mechanical Properties of Sintered PcBN

In this study, Polycrystalline cubic boron nitride (PcBN) composites were successfully synthesized via high-pressure and high-temperature (HPHT) sintering at 5.5 GPa and 1500 °C, using cBN and a Ti₂AlC/Al mixture as the raw material system. The effects of binder content and Ti₂AlC/Al ratio on the phase composition, microstructure, and mechanical properties of PcBN were systematically investigated. The primary reaction products were identified as TiC, TiB₂, and AlN. With increasing total binder content, the relative density, Vickers hardness, and fracture toughness of the PcBN composites initially increased and subsequently decreased. The composite with a cBN content of 80 wt.% exhibited an optimal combination of properties, achieving a relative density of 99.3%, a microhardness of 43.49 GPa, and a fracture toughness of 7.65 MPa·m1/2. Furthermore, at a constant Ti₂AlC content, an increase in Al content promoted the formation of TiB₂.