An investigation on the wear and subsurface deformation mechanism of CoCrFeMnNi high entropy alloy at subzero temperature

Developing high entropy alloys (HEAs) has opened up a new dimension of alloy design towards better properties than those of the existing ones. Recently, a single face-centered cubic HEA, CoCrFeMnNi, has received considerable attention due to its high strength, exceptional ductility, high hardness and outstanding fracture toughness at subzero temperatures. However, the wear and subsurface deformation mechanisms of this material under subzero temperatures have not been well understood. This work aims to explore the wear mechanisms and subsurface deformation behavior of CoCrFeMnNi at subzero temperatures down to −50 °C, with the aid of contact sliding on a tribometer using tungsten carbide balls of 6.5 mm in diameter. It was found that the HEA demonstrated abrasion wear behaviors with a lower wear rate at the room temperature. Many shear bands emerged in the neighborhood of the worn surface, indicating severe plastic deformation. It was also found that that at a subzero temperature, contact sliding would cause microstructural evolution and mechanical property variation in the subsurface.