Significant progress in the study on irradiation effects of high-temperature nickel-based alloys

Recently, the alloy irradiation research team of Shanghai Institute of Applied Physic has made significant progress in the study of the irradiation effect of nickel-based alloys. The synergistic evolution behavior and related mechanism of the two damage defects of helium bubble and dislocation loop in GH3535 alloy under dual-beam irradiation are revealed in detail. The paper entitled "In-situ TEM investigation on the evolution of He bubbles and dislocation loops in Ni-based alloy irradiated by H₂⁺ & He⁺ dual-beam ions", published in the Journal of Materials Science & Technology, a top journal in the field of materials science. The first author of the paper is Dr. Zhenbo Zhu, and the corresponding author is Prof. Hefei Huang.

The neutron irradiation in reactor is one of the main factors affecting the long-term stability of the structure and properties of metal materials. Due to the limitation of neutron irradiation conditions and experimental characterization techniques, the synergistic evolution mechanism of irradiation induced helium bubbles and dislocation loop is still unclear. In order to better simulate the neutron irradiation environment in molten salt reactor and study the evolution mechanisms of irradiation-induced defects in nickel-based alloy in detail, the GH3535 alloy was irradiated using H₂⁺ & He⁺ dual beam with in-situ TEM observations to explore the synergistic evolution mechanisms of the He-induced damage and displacement damage via their quantitative characterizations. Compared with the direct H₂⁺ & He⁺ dual-beam ions irradiated samples, the dislocation loops introduced during the H₂⁺ ion pre-irradiation can greatly change the evolution behavior of helium bubbles and dislocation loops which introduced by dual-beam ions irradiation: the interstitials and helium atoms introduced in the process of dual-beam irradiation are preferentially absorbed by the pre-existed dislocation loops, which contribute to the rapid growth of the dislocation loops and formation of bubble-dislocation loop complexes. Moreover, the loop-punching evolution behaviour and their emission are observed, while the related mechanism and their influence on subsequent microstructural evolution are studied in detail. In addition, the unfaulting mechanism of the Frank loops and evolution mechanism of rhombus-shaped loop in nickel-based alloy are revealed. This finding further deepened the understanding of the evolution behavior of irradiation damage defects in nickel-based alloys, and provided an important scientific basis for the optimization and evaluation of the irradiation performance of nickel base alloys.

This work was financially supported by the National Natural Science Foundation of China and the Youth Innovation Promotion Association, Chinese Academy of Sciences.

Link: https://doi.org/10.1016/j.jmst.2022.07.054

Figure Synergistic evolution mechanism of He bubbles and dislocation loops, including loop-punching mechanism and bubble-loop complexes, in Ni-based alloy irradiated by dual-beam ions were investigated via in-situ TEM.