Synergistic laser cladding and ion sulfurization strategy for in-situ FeS-WS2 solid lubrication film on CoCrFeNiW0.8 high-entropy alloy: Tribological system design and process-structure-property insight

This work employs ion sulfurization to fabricate a sulfide solid lubricating film on CoCrFeNiW 0.8 high-entropy alloy (HEA) coatings, aiming to enhance wear resistance and friction reduction. Systematic characterization reveals the HEA coating's multiphase composition (FCC, BCC, and α-phase) with an average hardness of 521 HV 0.2 . A 3.8 μm thick porous feather-like FeS-WS 2 solid lubricating film was formed on the surface of the CoCrFeNiW 0.8 HEA coating, and the bonding force of this film to the HEA coating reached 43.9 N. Tribological tests revealed that the ion sulfurized HEA exhibited a 73.3 % reduction in friction coefficient (from 0.45 to 0.12) and a wear rate reduced to 52.4 % of the untreated HEA (from 4.2 mg to 2.2 mg) under a 3 N applied load. The lubricating film maintains stable low friction (0.11–0.15) across 1.5–4.5 N loads but loses its friction-reducing ability when the normal load reaches 5 N. Wear mechanism analysis identifies distinct transitions: untreated HEA progresses from abrasive to abrasive-fatigue wear, while the sulfurized coating exhibits mild abrasive wear through synergistic FeS-WS 2 lamellar lubrication and HEA substrate support. This study develops a wear-resistant tribological system combining the CoCrFeNiW 0.8 HEA substrate and the in-situ FeS-WS 2 solid lubricant film with strong interfacial adhesion. The synergy between HEA design and ion sulfurization technology establishes a new strategy for high-performance anti-wear applications. • Hybrid laser cladding and ion sulfurization manufacture FeS-WS 2 sulfide solid lubrication film on HEA. • FeS-WS 2 sulfide solid lubrication film exhibits a porous feather-like microstructure. • Hard HEA matrix synergizes with soft sulfide film for low friction and wear. • FeS-WS 2 film prevents fatigue and oxidative wear effectively.