Tribological behavior and characteristics of TIG surface cladded AlCoCrFeNi high-entropy alloy on 304L stainless steel

Abstract

The present study examines the tribological properties of AlCoCrFeNi high-entropy alloy (HEA) surface cladded on 304L stainless steel via a Tungsten Inert Gas (TIG) heat source. Commercially pure powders of aluminum, cobalt, chromium, and nickel were ball-milled, mixed in specific ratios, and applied onto the substrate with polyvinyl alcohol as a binder. Cladding was performed with optimized parameters to create layers of HEA. Microstructural and EDS analysis revealed equiaxial dendrites rich in aluminum and nickel in dendritic (DI) areas, and rich in iron, chromium, and cobalt in interdendritic (ID) areas. Mixing entropy was calculated by consideration of EDS analysis of the cladding and based on the initial definition of a high-entropy alloy, the high-entropy nature of the cladding was confirmed. XRD analysis showed the presence of FCC, A2/B2, and hard σ phases. Surface alloyed material exhibited higher hardness compared to the base material, with an average of 540 HV versus 200 HV. A pin-on-disc wear test machine was used to assess tribological properties under different loads of 10, 20, and 40 N. The wear rates of the high-entropy cladded material were 36 and 50 % less than those of the 304L stainless steel under applied loads of 10 and 40 N, respectively, while their wear rates were almost similar at 20 N. Friction coefficients of HEA pins were notably lower than 304L at 10 and 20 N, with smoother profiles. Wear mechanisms of the HEA material varied with load: oxidative wear at 10 and 20 N due to the formation of an oxide layer, and abrasion and spallation at 40 N, resulting in a threefold increase in wear rate at this load. Overall, the study highlights the effectiveness of HEA cladding in improving tribological properties, especially under high applied load.