Decoding the interstitial/vacancy nature of dislocation loops with their morphological fingerprints in face-centered...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nuclear Engineering

Background:

• Dislocation loops are critical defects in irradiated materials, causing embrittlement and swelling.
• Identifying loop nature (interstitial- or vacancy-type) is crucial for understanding radiation damage.
• Current methods for distinguishing loop types are challenging and limited.

Purpose of the Study:

• To establish a correlation between the morphology of radiation-induced Frank loops and their nature (interstitial- or vacancy-type).
• To provide an efficient method for distinguishing loop types in face-centered cubic materials.
• To elucidate the underlying mechanisms governing loop morphology and stability.

Main Methods:

• Analysis of dislocation loop morphology in face-centered cubic materials under irradiation.
• Theoretical investigation of dislocation dissociation mechanisms.
• Correlation of observed loop shapes with their interstitial or vacancy nature.

Main Results:

• Circular Frank loops in face-centered cubic structures are consistently interstitial-type.
• Segmented Frank loops are vacancy-type in high stacking fault energy alloys but can be varied-type in low stacking fault energy and high-entropy alloys.
• Polygonal loop formation is linked to the energetically favorable dissociation of vacancy loops.

Conclusions:

• The morphology of radiation-induced Frank loops serves as a reliable indicator of their nature.
• This morphology-nature correlation offers an efficient and widely applicable method for defect characterization.
• The findings highlight the asymmetry in the behavior of vacancy and interstitial loops under irradiation.