Evolution of gas-filled nanocracks in crystalline solids

Area of Science:

• Materials Science
• Solid-State Physics
• Computational Materials Science

Background:

• Gas-filled cracks and nanovoids are critical defects in materials.
• Understanding their evolution under thermal and implantation conditions is essential for material performance.
• Helium-induced defects, particularly in silicon carbide (SiC), impact nuclear and semiconductor applications.

Purpose of the Study:

• To investigate the evolution of gas-filled cracks under gas implantation and annealing.
• To elucidate the mechanism limiting the growth of helium-filled nanocracks in SiC.
• To model the formation and Ostwald ripening of bubble-loop complexes.

Main Methods:

• Utilizing an elastic continuum approach to model crack evolution.
• Analyzing the stabilization of nanocracks by dislocation dipole formation.
• Developing a model for gas atom and matrix atom exchange in bubble-loop complexes.

Main Results:

• Demonstrated that circular dislocation dipoles stabilize helium-filled nanocracks in SiC, limiting their growth.
• Modeled the formation and Ostwald ripening of bubble-loop complexes via coupled atom exchange.
• Derived scaling laws for bubble and loop size evolution that agree well with experimental observations.

Conclusions:

• The stabilization mechanism by dislocation dipoles provides a key explanation for observed growth limitations.
• The developed model accurately captures the complex interplay of gas and matrix atom diffusion.
• The findings offer insights into defect evolution in irradiated materials, relevant for SiC applications.