Black dot defects as drivers of microstructural evolution in alpha-iron under irradiation

L Guo and BB Liu and J Gao and F Gao and HQ Deng, ACTA MATERIALIA, 297, 121316 (2025).

DOI: 10.1016/j.actamat.2025.121316

This study investigates the role of black dot defects in the radiation- induced microstructural evolution of alpha-iron by combining density functional theory, molecular dynamics simulations, and a cluster dynamics model. The model incorporates the temperature-dependent stability and free energy of C15 clusters, defect transformations, and the effects of stress fields on defect interactions. The results replicate the experimental dominance of 1/2(111) dislocation loops at 300 degrees C and predict a high density of black dot defects, which are often overlooked in experiments. A defect density progression mechanism is identified, where defect density transfers from small black dot defects to larger loops during irradiation. The study reveals that the dominance of (100) loops at high temperature is driven by black dot defect stability and long-term dynamics. Additionally, it highlights the role of dislocation networks in stabilizing (100) dislocation loops under high-dose irradiation.

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