Nano-tribological behavior of high-entropy alloys CrMnFeCoNi and CrFeCoNi under different conditions: A molecular dynamics study

Attributed to their superior properties over the conventional alloys, high-entropy alloys (HEAs) have attracted considerable interest. One of HEAs' attractive properties is their high wear resistance. Although considerable research on wear of HEAs can be found in the literature, understanding of the responses of HEAs to different wearing conditions needs to be enhanced in order to utilize HEAs effectively. For instance, studies on nano-wear and nano/micro-machining under different conditions are rare, which influences the extension of HEAs' applications to nanotechnological areas, e.g., nano/micro-devices and nano-manufacturing. In this study, we conducted molecular dynamics simulations to investigate responses of CrMnFeCoNi and CrFeCoNi HEAs to wear under unidirectional and bi-directional sliding conditions, respectively, for two nano-wearing processes. One process is similar to nano-machining and the other is sliding wear on nano-scale under a light normal force. Due to its higher hardness, the Mn-free HEA is more resistant to wear than the Mn-containing one. During the simulated nano-machining process, both the alloys were worn more under the bi-directional sliding condition. While the situation was reversed during the sliding wear process, in which the bi-directional sliding caused less wear. Bauschinger's effect plays a role in influencing the wear behavior of the HEAs under the different conditions. This work provides an insight into nano-tribological behaviors of the alloys under different wearing conditions, helping either mitigate wear of HEAs or improve their machining efficiency.