Interaction between dislocations and L1₂ precipitates in the Al_0.3CoCrFeNi high-entropy alloy during nanoscratching

The Al_0.3CoCrFeNi high-entropy alloy (HEA) containing L1₂ precipitates (Ni₃Al) has garnered significant attention due to their exceptional mechanical properties and cost-effectiveness. While the strengthening effects of L1₂ precipitates on mechanical performance are well-documented, their role in tribological behavior remains underexplored. This study employs molecular dynamics (MD) simulations to systematically investigate the influence of L1₂ precipitates on the nanoscratching behavior of Al_0.3CoCrFeNi HEA. Comparing the substrate without L1₂ precipitates, L1₂ precipitates alter dislocation dynamics, reducing total dislocation length while enhancing tribological performance. Debris atoms exhibit a more uniform morphology and reduced pile-up height, leading to a lower wear rate. In addition, increasing scratch velocity and deeper scratches all intensify dislocation-precipitate interactions, promoting residual dislocations in L1₂ precipitates and asymmetric debris distribution. In particular, the interaction between dislocation and L1₂ precipitates during nanoscratching was revealed by the well-designed shear simulation. L1₂ precipitate exerts a delaying effect on dislocation motion rather than a pinning effect, which can improve strength while maintaining ductility. Meanwhile, the strengthening effect of L1₂ precipitates exhibits an overall upward trend as the dislocation cuts through multiple times, which provides potential work hardening ability. These results elucidate the dual role of L1₂ precipitates in enhancing both strength and wear resistance, providing critical insights for designing high-performance HEAs.