Nanotribological behaviors of high-entropy alloys CoCrFeMnNi and medium-entropy alloys Ni0.4Al0.3Co0.3, Ni0.4Cr0.3Fe0.3 under different conditions: A molecular dynamics study

High-entropy alloys (HEAs) and medium-entropy alloys (MEAs) have great potential for practical engineering applications in aerospace, rail transit, oil and gas equipment and other key fields due to their excellent physical and mechanical properties. However, there are relatively few studies on the wear resistance and mechanism of high-entropy alloys and medium-entropy alloys. In this paper, based on molecular dynamics (MD) simulation, the friction and wear behavior and influence mechanism of CoCrFeMnNi (HEA), Ni0.4Al0.3Co0.3, and Ni0.4Cr0.3Fe0.3 (MEAs) under different conditions were compared. Interestingly, the results show that the Ni0.4Cr0.3Fe0.3 alloys exhibits the lowest coefficient of friction and lowest wear under the same friction conditions. The CoCrFeMnNi alloy demonstrates relatively good wear resistance at higher velocities and deeper penetration depths due to its HCP phase structure and the "V"-shaped shear bands that help dissipate stress and shear strain during the friction process. In addition, further research found that the proportion of Ni element is one of the key factors to determine the wear resistance of high-entropy alloy CoCrFeMnNi. As the growth of the proportion of Ni element, the accumulation height and CSP value in the alloy will gradually decrease, and eventually lead to the enhancement of the wear resistance of high-entropy alloy CoCrFeMnNi.