Deciphering the Effect of Co/Cr Ratio on the High-Temperature Friction of Co x Cr 40– x FeNiTi High-Entropy Alloys: Atomic-Scale Study

Friction and wear pose significant concerns for moving mechanical components. In this context, CoCrFeNiTi high-entropy alloys (HEAs) have attracted considerable interest owing to their exceptional wear resistance. In this study, through molecular dynamics simulations, investigates the effects of Co/Cr ratio and temperature on the friction behavior of the alloy. The results show that, at room temperature, wear resistance increases nonlinearly with the Co/Cr ratio. Specifically, compared to the alloy with 5% Co and 35% Cr, the alloy with 35% Co and 5% Cr shows reductions of 60.6% in worn atom count, 8.3% in friction force, and 8.5% in friction coefficient. This improvement is attributed to the increased Co/Cr ratio, which elevates the content of hardening phases and raises dislocation density, thereby strengthening the material. When the temperature rises from 300 to 600 K, the friction coefficient enhances to 0.99 (a 41.4% increase), accompanied by the disappearance of BCC and HCP twin structures, a reduction in dislocations, and weakened atomic bonding, resulting in a decrease in wear resistance. This study reveals the mechanisms by which Co/Cr ratio and temperature affect the friction behavior of Co x Cr 40– x FeNiTi HEAs, providing a theoretical basis for the design of high-temperature wear-resistant HEAs.