Tunable mechanical properties of high-entropy alloy nanoparticles with core-shell structure

Core-shell high-entropy alloy (HEA) nanoparticles exhibit broad applications in fields such as catalysis and energy storage, owing to their tunable composition, high stability, and multifunctionality. In present study, the mechanical properties of core-shell HEA nanoparticles are investigated via atomic simulations. It is revealed that shell thickness plays a key role in tuning both the elastic modulus and yield strength of nanoparticles. If the shell thickness is below a critical threshold, these mechanical properties show a strong dependence on the shell thickness. In contrast, when the shell thickness exceeds this threshold, the elastic properties nearly remain constant. A simple theoretical model is proposed and successfully predicts the critical shell thickness. Moreover, the plasticity in nanoparticles also depends on shell thickness. For shell thicknesses below approximately half the outer radius, phase-transition is a dominant deformation mechanism in the core, and contributes significantly to overall plasticity. When the shell thickness exceeds half of the particle radius, phase-transition in the core is suppressed, and overall plasticity is primarily sustained by dislocation slip in the shell. These findings provide valuable insights into tuning the mechanical performance of core-shell HEA nanoparticles through controlling the geometrical design.