Opposite Bauschinger Effects on Wear of High-Entropy Alloy AlCoCrFeNi_x (x = 0 to 2) Under Sliding Wear and Machining Conditions

Bauschinger effect on wear of high-entropy alloy (HEA), AlCoCrFeNi_x (x = 0 to 2), was studied with the aim of verifying a hypothesis: Bauschinger effect affects sliding wear and machining wear oppositely. Wear tests were performed with two counter-parts, \({\text{Si}}_{3} {\text{N}}_{4}\) ${\text{Si}}_3{\text{N}}_4$ ball and diamond tip, which simulated sliding wear and machining wear conditions. With the former, bi-directional sliding resulted in less wear than unidirectional sliding, while the trend was opposite when the diamond tip was used, thus verifying the hypothesis. With increasing Ni content, the difference in wear between bi-directional and unidirectional sliding processes was enlarged, ascribed to enhanced Bauschinger effect due to increased plasticity of the AlCoCrFeNi_x alloy. Molecular dynamics simulations were implemented to elucidate underlying mechanisms. The study helps take the advantage of Bauschinger effect via tailoring the microstructure of high-entropy alloys, which have demonstrated to have high engineering values, and other materials as well for effective wear control and efficient material machining or manufacturing.