Multiscale modelling of plastic flow localization in irradiated materials

Area of Science:

• Materials Science
• Nuclear Engineering
• Computational Physics

Background:

• Energetic particle irradiation significantly degrades mechanical properties of metals, including increased yield stress and reduced ductility.
• These effects are critical for nuclear power plant pressure vessels and fusion energy materials, but fundamental mechanisms remain unclear.
• Plastic flow localization is a key consequence of irradiation, impacting material performance and lifespan.

Purpose of the Study:

• To elucidate the fundamental mechanisms of plastic flow localization in irradiated metals.
• To demonstrate the relationship between irradiation fields and observed mechanical property degradation.
• To reveal the processes governing plastic flow localization in defect-free channels within irradiated metals.

Main Methods:

• Utilized three-dimensional multiscale simulations.
• Modeled the behavior of irradiated metals under stress.
• Investigated dislocation dynamics and interactions with irradiation-induced defects.

Main Results:

• Observed dislocation pinning by irradiation-induced defect clusters.
• Demonstrated subsequent dislocation unpinning through defect absorption.
• Identified cross-slip of dislocations as a stress-dependent mechanism.
• Found that plastic flow channel width is limited by interactions between dislocation dipoles and defect clusters.

Conclusions:

• The study reveals the detailed mechanisms of plastic flow localization in irradiated metals.
• Dislocation dynamics and defect interactions are key to understanding irradiation-induced mechanical property changes.
• Simulation results provide fundamental insights into material behavior under irradiation, crucial for nuclear and fusion applications.