Elucidating the machining mechanism of polycrystalline high-entropy alloys nanowires by nanoskiving

Controllable nanoskiving of Pt-based high-entropy alloy nanowires is hindered by chemical disorder, lattice distortion, and grain-boundary heterogeneity. In this work, molecular dynamics simulations are performed to reveal the atomistic cutting mechanism of polycrystalline PtPdCuAgAu high-entropy alloy nanowires, with emphasis on grain-boundary effects and cutting-depth-dependent size effects. Shockley dislocations nucleate at the tool tip and accumulate near grain boundaries, leading to local stress concentration, heterogeneous plastic flow, surface roughening, and thickness fluctuation. Compared with the monocrystalline counterpart, the polycrystalline system shows larger dimensional deviations due to anisotropic grain responses. Cutting force increases with cutting distance because of solid-solution strengthening, lattice distortion, and grain-boundary obstruction. Decreasing cutting depth exponentially increases thickness deviation and specific cutting energy. These findings clarify the nanoskiving mechanism of high-entropy alloy nanowires and provide guidance for their precise fabrication.