The Evolution of Structural Defects under Irradiation in W by Molecular Dynamics Simulation

Area of Science:

• Materials Science
• Nuclear Engineering
• Computational Physics

Background:

• Tungsten (W) is a candidate material for plasma-facing components in fusion reactors due to its radiation resistance.
• Nanocrystalline materials with high grain boundary density may offer superior radiation damage resistance compared to coarse-grained counterparts.
• The precise mechanisms governing grain boundary interactions with radiation-induced defects remain poorly understood.

Purpose of the Study:

• To investigate the evolution of radiation-induced defects in single-crystal and bicrystal tungsten.
• To elucidate the role of grain boundaries in defect dynamics under irradiation.
• To assess the influence of temperature and primary knocked atom (PKA) energy on defect evolution.

Main Methods:

• Molecular dynamics (MD) simulations were employed to model irradiation processes.
• Simulations covered a temperature range of 300–1500 K.
• Primary knocked atom (PKA) energies were varied from 1 to 15 keV.

Main Results:

• Defect generation is more sensitive to PKA energy than temperature.
• Higher PKA energy leads to an increased number of defects during thermal spike stages.
• Grain boundaries impede defect recombination and promote vacancy clustering in bicrystal tungsten.
• Interstitial atoms exhibit a strong tendency to segregate at grain boundaries.

Conclusions:

• Grain boundaries play a significant role in mitigating radiation damage by altering defect evolution pathways.
• Understanding grain boundary behavior is essential for designing radiation-tolerant tungsten components for fusion energy applications.
• MD simulations provide valuable insights into the fundamental interactions between defects and grain boundaries in irradiated materials.