Dry Sliding Wear Behavior of Al_0.4FeCrNiCo_x(x = 0, 0.25, 0.5, 1.0 mol) High-Entropy Alloys

This study aims to investigate the dry sliding wear behavior of Al_0.4FeCrNiCo_x(x = 0, 0.25, 0.5, 1.0 mol) high-entropy alloys (HEAs) at room temperature by varying sliding speed and normal load. X-ray diffraction studies indicate that the BCC phase decreases and completely disappears as cobalt content increases from x = 0–1.0 mol. Correspondingly, the hardness of the proposed alloys decreases from 377.7 to 199.5 HV with the addition of cobalt content from x = 0–1.0 mol. The wear analysis indicates that the highest specific wear rate occurs in the case of Al_0.4FeCrNiCo_x=1 HEA with varying sliding velocity and normal load, respectively. The worn surface was analyzed by using scanning electron microscopy with attached energy-dispersive X-ray spectroscopy, 3D profiling, and X-ray photoelectron spectroscopy (XPS) in order to understand the wear mechanism and oxides formed during the wear process. Results indicated that the wear occurred due to adhesion along with delamination, plastic flow, and oxidative wear. XPS results indicate that the presence of Al₂O₃, Fe₂O₃, Cr₂O₃, and Co₃O₄ oxides formed on the worn surface.