The effects of helium bubbles on the plastic deformation and fracture behavior of crystal/amorphous nanocomposites

Molecular dynamics (MD) simulations were carried out to study the plastic deformation and fracture behavior of nanoscale Cu/CuZr core-shell crystal/amorphous (CA) models and a nanocrystalline (NC) Cu model before and after helium (He) irradiation. The simulation results indicate that, regardless of whether the models are pre-irradiated or irradiated, the CA structure demonstrates superior plasticity and fracture resistance compared to the NC structure. Moreover, the plasticity and fracture behavior of the CA structure exhibit amorphous layer thickness dependents. Analysis of the crack models after irradiation further reveals that models with thicker amorphous layers possess better ability to passivate the crack tip, and the presence of He bubbles does not alter this outcome. As amorphous layer thickness increases, there is a mechanism transition from dislocation-shear transformation zone (STZ) interaction to shear banding controlled process, corresponding to the observed changes in strength, plasticity, and deformation behaviors. Overall, the proposed CA structure shows reduced sensitivity to the expansion of He bubbles and contributes to its higher crack tip passivation ability, providing atomic-scale theoretical support for the development of CA structural materials with better radiation resistance.