Study on damage defects of Cr coating on Zr alloy surface irradiated by high-dose Au2+: HRTEM observation and molecular dynamics simulation

A Yan and BF Luan and HL Zhou and CQ Liu and LJ Chen and XL Yang and XY Zhu and F Zhang and CR Xu and C Sun and HB Ruan and WJ Huang, JOURNAL OF ALLOYS AND COMPOUNDS, 1011, 178366 (2025).

DOI: 10.1016/j.jallcom.2024.178366

Cr-coated Zr alloys have garnered attention for their potential use in accident-tolerant fuel cladding, owing to their excellent oxidation and corrosion resistance. However, their radiation resistance under extreme reactor conditions remains largely unexplored. This study employed high- resolution transmission electron microscopy (HRTEM) and molecular dynamics (MD) simulation to systematically investigate the effects of high-dose Au2+ irradiation on the microstructure of body-centered cubic (BCC) Cr coatings on Zr alloy surfaces at room temperature. The experimental results showed that a significant number of dislocation loops and defect clusters formed in the irradiated damage region. HRTEM and MD analyses confirmed that the "black spot" defects corresponded to high-density dislocation loops, mainly of the 1/2 < 111 > type. Moreover, MD simulations revealed that, as irradiation damage increased, interstitial atomic clusters grew by absorbing surrounding point defects, while vacancy clusters remained small and uniformly distributed due to their higher migration energy. Additionally, dislocation loops could either grow or disappear during irradiation by absorbing point defects or through overlapping cascade collisions. This study provides new insights into the effects of irradiation damage on the microstructure of Cr coatings.

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