Mo‐Based Multiphase Interface Design for PcBN Composites: Enhanced Interfacial Bonding, Mechanical, and Cutting Performances

Polycrystalline cubic boron nitride (PcBN) is a widely used superhard material for high‐performance cutting tools. A critical challenge in its development lies in maintaining high hardness while enhancing fracture toughness under high‐speed vibration and impact conditions. In this work, composite binders consisting of Co, Al, and Mo were adopted with a total binder content fixed at 30 wt% and a constant Co/Al mass ratio of 3:1. Samples with different Mo contents were fabricated via conventional powder mixing and sintering processes. A Mo‐based multiphase interface design was employed to optimize the interfacial bonding strength, mechanical properties, and cutting performance of cBN/Co/Al/Mo composites. The results demonstrate that the sample with 6 wt% Mo exhibits the optimal comprehensive performance: Its flexural strength reaches 1626 MPa and Vickers hardness is 3905 HV, and no cracks emerge under an impact energy of 50 J. Its overall performance outperforms most commercial PcBN cutting tools, achieving synergistic improvement of hardness and toughness. Dry cutting tests on Cr12 steel show that Mo addition effectively improves the damage resistance of the material, and the flank wear is obviously reduced after a cumulative cutting distance of 3000 m. This study offers a practical technical route for preparing high‐performance PcBN cutting tools applicable to harsh intermittent cutting environments.