Influence of symmetric tilt grain boundaries and/or Cr-rich α′ precipitates on irradiation damage in Fe-Cr-Al alloys: A molecular dynamics investigation

DT Zheng and D Chen and HS Zhao and LZ Li and ZH Guo and ZC Zhao and HQ Deng, JOURNAL OF NUCLEAR MATERIALS, 616, 156090 (2025).

DOI: 10.1016/j.jnucmat.2025.156090

Recently, Fe-Cr-Al alloy is considered one of the most prospective accident-tolerant fuel cladding materials. However, Fe-Cr-Al alloy exposed to fast neutron environments exhibits microstructural features, which leads to material embrittlement, decreases mechanical properties, and affects its service performance. In the present work, molecular dynamics (MD) methods are employed to simulate the irradiation performance of three Fe-Cr-Al alloy systems, namely alloys containing grain boundary (alloy-GB systems), alloys containing Cr-rich alpha ' phase (alloy-alpha ' systems), and alloys containing GB and Cr-rich alpha ' phase (alloy-GB-alpha ' systems). The GB energies (EGB) for different symmetric tilted grain boundaries (STGBs) are calculated. The STGBs with high EGB exhibit more point defects and lower defect annihilation rate than those with low EGB. And the defect annihilation rate of STGB with low EGB is high with fewer defects surviving in the bulk. Moreover, the number of vacancies in the bulk is always greater than the number of interstitials. For the alloy-alpha ' systems containing the Cr-rich alpha ' phase with the 001 orientation, the increases in temperature and the distance of PKA from the center of the Cr-rich alpha ' phase (dPKA-alpha ') will reduce the degree of irradiation damage. The increases in the size and the Cr content of the Cr-rich alpha ' phase will enhance the degree of irradiation damage. For the alloy-GB-alpha ' systems with Sigma 19(116)110 GB, the number of final surviving defects is greater than that in the alloy-GB systems, which indicates that the interaction of GB and Cr-rich alpha ' phase will further increase the degree of irradiation damage. The increases of dPKA-GB will deepen the degree of irradiation damage when the PKA atom is located in/beyond the Cr-rich alpha ' phase. Moreover, the dislocations form on the GB for the alloy-GB-alpha ' systems with Sigma 19(116)110. The appearance of dislocation can significantly affect the defect behaviors in the irradiation damage, which results in a decrease in the number of defects and defect clustering rate.

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