Interfacial Wear Reduction of Porous CoNiCrFeMn High-Entropy Alloys: An Atomic-Scale Study

Pores are common processing defects, yet their effects on the mechanical and tribological properties of high-entropy alloys (HEAs) remain unclear. In this study, molecular dynamics simulations were conducted to systematically explore the influence of pore size on mechanical behavior and deformation mechanisms of a single-crystal FCC CoNiCrFeMn HEA during nanoindentation and scratch processes. Introducing pores leads to a noticeable decrease in hardness and a rise in potential energy, ultimately promoting greater deformability. During scratch, porous models exhibit lower friction forces and fewer wear atoms, exhibiting beneficial wear reduction properties. Compared to dense counterparts, porous structures induce localized shear concentrations around pores. Larger pores offer more space for accommodating plastic deformation and are correlated with a reduced dislocation density near the contact region. Furthermore, pores act as efficient dislocation barriers, restricting their propagation within the alloy matrix. By varying the simulation temperature and scratch speed, we further analyze their effects on deformation behavior in porous HEAs. Elevated temperatures intensify atomic rearrangements, causing pronounced material softening and reduced dislocation density. Conversely, higher scratch speeds increase frictional force and indentation load and weaken crystal plasticity.