Comparison of the Sliding Wear of Single-Phase F.C.C Carbon-Doped Fe40.4Ni11.3Mn34.8Al7.5Cr6 and CoCrFeMnNi High-Entropy Alloys with AISI 316 Stainless Steel at Cryogenic Temperatures

Recent studies have shown that the excellent mechanical properties of high entropy alloys (HEAs) can be enhanced at cryogenic temperatures, making them potential candidates for low-temperature applications. However, very limited work has been done on understanding their cryogenic wear mechanisms. In this study, the sliding wear behavior of two f.c.c. HEAs, carbon-doped Fe40.4Ni11.3Mn34.8Al7.5Cr6 (CHEA) and equiatomic CoCrFeMnNi (Cantor alloy) were determined against a yttria-stabilized zirconia counterface at cryogenic temperatures. Sliding wear tests were run both in dry cryogenic sliding conditions and under liquid nitrogen cryogenic conditions (wet conditions). Scanning electron microscopy and energy dispersive x-ray analysis were used to characterize worn pin surfaces. The worn surfaces for each material type and condition showed evidence of plastic deformation and oxide formation. X-ray photoelectron spectroscopy further identified the different oxide types and was able to provide greater understanding on how specific oxides contribute to the wear behavior under each condition. Additionally, scanning transmission electron microscopy and atom probe tomography were used for CHEA and Cantor alloy samples to offer insight into the elemental distribution at a nanoscale and the precipitation of any second phases. These results were compared with previous room temperature tests and with 316 stainless steel, a current material of choice for many cryogenic applications, at both room and cryogenic temperatures.