In-situ TEM investigation on the evolution of He bubbles and dislocation loops in Ni-based alloy irradiated by H2+ &
In-situ TEM investigation on the evolution of He bubbles and dislocation loops in Ni-based alloy irradiated by H2+ &
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DOI：
10.1016/j.jmst.2022.07.054
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发表时间：
2022-09
期刊：
影响因子：
--
通讯作者：
Zhenbo Zhu;Wei Ji;Hefei Huang
中科院分区：
文献类型：
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作者：
Zhenbo Zhu;Wei Ji;Hefei Huang
利用透射电镜原位研究了熔盐堆最有希望的候选结构材料GH3535合金在650° C、30keVH2 + & He+双束离子辐照下He泡和位错环的协同演化机制.详细表征了位错环和He泡的形核、合并和尺寸变化，研究了辐照能量密度和预先存在的位错环对其演变的影响。氦泡和位错环的数密度迅速增加，随后饱和，而它们的尺寸不断增加，随着离子注量的增加。在双束离子辐照过程中，具有强吸收特性的位错环优先生长，抑制位错环的形核。此外，气泡倾向于在位错环内形核，形成气泡环复合体，然后其数密度降低。讨论了Frank环的非断裂过程，其中两类环的能量差以及内部Shockley位错环的演化控制了非断裂行为。揭示了环穿孔机制的几个演化阶段，发射环可以直接形成完美环，也可以对相邻的Frank环进行非故障处理。环内的He气泡为菱形环的形成提供了相应的应力，菱形环通过与相邻环的合并可以实现快速生长和扫描能力。此外，它的解离肖克利位错可以unfault弗兰克环沿着其滑动方向。在四种弗兰克环变体中，边缘弗兰克环变体具有最高的生长速率，其次是完美环。在现场实验观测的基础上，对相关机理进行了深入探讨。
The synergistic evolution mechanisms of He bubbles and dislocation loops under 30 keV H 2+ & H e+ dual-beam ions irradiation at 650° C in the Ni-based alloy GH3535, which is the most promising candidate structure material for molten salt reactors (MSRs), were revealed via in-situ TEM. The nucleation, merging, and change in the size of the dislocation loops and He bubbles were characterized in detail to study the influences of irradiation fluence and pre-existing dislocation loops on their evolutions. The number density of both the He bubbles and dislocation loops increases rapidly and subsequently saturates, whereas their size continuously increases with the increasing ion fluence. Pre-existing dislocation loops with strong absorption characteristics grow preferentially and suppress the nucleation of dislocation loops during the dual-beam ions irradiation. Moreover, the bubbles tend to nucleate within the dislocation loops to form bubble-loop complexes, and then decrease in their number density. The details of the unfaulting processes of the Frank loops were discussed, where the energy difference between the two types of loops as well as the evolution of the inside Shockley dislocation loops dominates the unfaulting behavior. The several evolution stages of the loop-punching mechanism are revealed, and the emitted loops can directly form perfect loops as well as unfault the neighboring Frank loops. The He bubbles inside the loops provide corresponding stress for the formation of rhombic loops, which can achieve rapid growth and sweep ability by merging with the neighboring loops. Additionally, its dissociation to Shockley dislocation can unfault the Frank loops along their slip direction. Among the four Frank loop variations, the edge-on Frank loop variations have the highest growth rate, followed by the perfect loop. The related mechanisms based on in-situ experimental observation are discussed in depth.