Building up coherent interfaces in Cu-WS₂ composite via Co doping to achieve synergistic enhancement of mechanical and tribological properties

A novel Co doping strategy is developed for Cu-WS₂ composite using SPS. • Co doping induces in-situ formation of Co 3 W with coherent interfaces. • Coherent interfaces suppress crack initiation and enhance lubricant stability. • CWC-Co exhibits low friction and wear rate due to coherent interfaces. • Synergistic improvement in mechanical and tribological properties is achieved. Overcoming the inherent conflict between mechanical and tribological properties has long been a critical challenge in designing Cu-based self-lubricating composites. This study presents a strategy based on coherent interfaces to resolve this trade-off and achieve superior synergy. Minor Co doping in a Cu-WS₂ composite triggers an in-situ reaction, converting the abrasive decomposition product W into a reinforcing Co 3 W intermetallic phase. This constructs a unique “Cu/Co 3 W/Cu 2 S” multiphase structure where Co 3 W forms coherent interfaces with both the Cu matrix and the Cu 2 S lubricant, exhibiting ultralow lattice mismatches of 3.4% and 2.3%, respectively. These coherent interfaces not only provide strong interfacial bonding strength but also form a semi-encapsulating structure that effectively anchors the lubricant phase. Consequently, the composite achieves a superior combination of a high compressive strength of 655 MPa, bending strength of 448 MPa, with a low friction coefficient of 0.24 and wear rate of 4.20 × 10 −6  mm 3 ·N −1 ·m −1 . This work provides new insights into the innovative design of high-performance metal matrix self-lubricating composites via a coherent-interface strategy that resolves the long-standing property conflict.