Dislocation dynamics in noble-metal high-entropy alloys under nanoindentation: Neuroevolution potential insights

Abstract

Neuroevolution-potential molecular-dynamics simulations reveal that stacking-fault-energy (SFE) governs nanoindentation plasticity in the noble alloys, AuPdAg and AuPdAgPt. The addition of platinum increases the SFE, delaying Shockley partial nucleation and suppressing early prismatic dislocation loop formation. AuPdAgPt therefore exhibits dense dislocation tangling and sessile junctions, reduced frequency of plastic events, and enhanced deformation resistance via forest hardening. In contrast, AuPdAg shows burst-like plasticity with dislocation density decaying due to loop annihilation. These results establish the SFE as a key descriptor for dislocation-mediated plasticity in noble-metal high-entropy alloys.