Microstructural and tribological characteristics of TIG surface cladded AlCoCrFeNi2.1Tix high-entropy alloys on ductile iron

This study investigates the surface cladding of AlCoCrFeNi 2.1 Ti x (x = 0.1, 0.5, 1) high-entropy alloys (HEAs) on ductile iron using Tungsten Inert Gas (TIG) as a heat source. High-purity aluminum, cobalt, chromium, nickel, and titanium powders were initially ball-milled in predetermined ratios and subsequently pre-placed on the substrate using polyvinyl alcohol as a binder. The cladding process was optimized to achieve dilution rates of 18 %, 17 %, and 16 % for titanium molar ratios of 0.1, 0.5, and 1, respectively, ensuring the desired chemical composition. Crystallographic analysis confirmed FCC + BCC dual-phase structures with dendritic and interdendritic morphologies and TiC precipitates. Hardness measurements indicated values of 470 HV, 525 HV, and 758 HV for Ti 0.1 , Ti 0.5 , and Ti 1 claddings, respectively, compared to 340 HV for the base metal. Tribological behaviors were evaluated through pin-on-disc wear tests at 5, 10, and 20 N against AISI 52100 steel disc. The Ti 1 cladding exhibited lower wear rates than those of the substrate, by approximately 58 %, 6 %, and 24 % at 5, 10, and 20 N, respectively. The friction coefficients of the HEA cladding were higher than those of the base material at 5 and 10 N, while at the higher load of 20 N, it was lower than that of the base material by around 28 %. The dominant wear mechanism on the HEA-clad surface transitioned from oxidative wear at 5 N to a combination of abrasive and oxidative wear at 10 N, and ultimately to mainly abrasive wear at 20 N.