A Phase-Field Study of Microstructure Evolution in Tungsten Polycrystalline under He/D Irradiation

Area of Science:

• Materials Science
• Nuclear Engineering
• Physics

Background:

• Tungsten (W) is a key material in fusion reactors due to its high melting point and low sputtering yield.
• Understanding microstructural evolution under plasma exposure (He/D irradiation) is critical for fusion reactor longevity.
• Previous models have not fully captured the complex microstructural changes induced by varying irradiation energies.

Purpose of the Study:

• To characterize the evolution of tungsten microstructure under helium/deuterium irradiation.
• To establish an empirical relationship between fractal dimension and irradiation energy.
• To implement this relationship in a phase-field model for predicting void evolution.

Main Methods:

• Fractal dimension analysis was used to quantify microstructural patterns under low (10-80 eV) and high (8-30 keV) irradiation energies.
• An empirical relation was derived linking fractal dimension changes to irradiation energy.
• A phase-field model was developed incorporating interfacial energy and the derived empirical relation.

Main Results:

• A direct correlation was observed between the fractal dimension of W microstructures and irradiation energy.
• The study established an empirical relation for microstructural change as a function of irradiation energy.
• The phase-field model successfully captured void nucleation, growth, and sink efficiency at grain boundaries.

Conclusions:

• Fractal dimension analysis provides a robust method for characterizing irradiated tungsten microstructures.
• The developed empirical relation and phase-field model offer improved predictive capabilities for tungsten's behavior under fusion-relevant irradiation conditions.
• This research contributes to the design and material selection for future fusion energy devices.