Regulating Vacancy Formation Energy and Interface Reaction to Achieve Excellent Mechanical and Tribological Properties of Cu/WS ₂ Composite Alloying With Sn

Achieving a simultaneous enhancement in both tribological and mechanical properties of self‐lubricating composites has long been a challenge. In this study, we designed the composition based on first‐principles calculation and fabricated a copper‐based self‐lubricating composite with excellent tribological and mechanical properties via spark plasma sintering. Results show that the Cu/WS 2 composite alloying with 8 at% Sn exhibits a low friction coefficient of 0.17, a wear rate two orders of magnitude lower than that of the one without Sn addition, along with significantly improved compressive strength and hardness. This exceptional performance is primarily attributed to the Sn solid solution, through the increase in vacancy formation energy () of copper atoms from 1.11 to 1.37 eV. It effectively suppresses the decomposition of WS 2 and leads to the formation of a semi‐coherent metastable phase of Cu 2 WS 4− x . This phase notably enhances the compressive strength from 466 to 716 MPa. Besides, the highly retained WS 2 (> 70%) ensures self‐lubrication during sliding. In contrast, elements characterized by a decrease in , such as Ni, promote the decomposition of WS 2 , thereby degrading the tribological properties of the Cu/WS 2 composite.