Helium-hydrogen synergistic effects on swelling in in-situ multiple-ion beams irradiated steels*

Abstract

The development of reliable fusion energy is one of the most important challenges in this century. The accelerated degradation of structural materials in fusion reactors caused by neutron irradiation would cause severe problems. Due to the lack of suitable fusion neutron testing facilities, we have to rely on ion irradiation experiments to test candidate materials in fusion reactors. Moreover, fusion neutron irradiation effects are accompanied by the simultaneous transmutation production of helium and hydrogen. One important method to study the He–H synergistic effects in materials is multiple simultaneous ion beams (MSIB) irradiation that has been studied for decades. To date, there is no convincing conclusion on these He–H synergistic effects among these experiments. Recently, a multiple ion beam in-situ transmission electron microscopy (TEM) analysis facility was developed in Xiamen University (XIAMEN facility), which is the first triple beam system and the only in-running in-situ irradiation facility with TEM in China. In this work, we conducted the first high-temperature triple simultaneous ion beams irradiation experiment with TEM observation using the XIAMEN facility. The responses to in-situ triple-ion beams irradiation in austenitic steel 304L SS and ferritic/martensitic steel CLF-1 were studied and compared with the results in dual- and single-ion beam(s) irradiated steels. Synergistic effects were observed in MSIB irradiated steels. Helium was found to be critical for cavity formation, while hydrogen has strong synergistic effect on increasing swelling.

Helium-Hydrogen Synergistic Effects in Structural Materials Under Fusion Neutron Irradiation

“…The increase of swelling caused by He-H synergistic effects in materials under different experimental conditions had been demonstrated in previous studies (Farrell and Lee, 1985;Farrell and Lee, 1987;Sekimura et al, 2000;Tanaka et al, 2004;Borodin et al, 2013;Brimbal et al, 2015;Kupriiyanova et al, 2016;Liu et al, 2021). However, some results (Farrell et al, 1978;Hamada et al, 1997;Kupriiyanova et al, 2016;Jiang et al, 2020) showed that He-H synergistic effects on swelling are not monotonic, indicating that the swelling may not always be enhanced but also be suppressed under triple beam irradiation.…”

“…In the column of "the effect of He" in Table 1, the presence of He in dual-beam irradiation increases the density and decreases the size of cavities in almost all cases. Besides, in some studies (Brimbal et al, 2015;Liu et al, 2021), researchers observed no cavities in materials under single HI irradiation, while cavities emerged under dual beam (HI + He) irradiation. This indicates the role of He in prompting cavity nucleation.…”

“…As a result, cavities might transform between void-like and bubble-like as the temperature changes. And these two types of cavities, which differ in size and shape, are often observed to coexist in materials after irradiated in the study of He-H synergistic effects (Taller et al, 2019;Liu et al, 2021). Roldán et al (2016) reported that, in irons irradiated by triple-ion beam, as the temperature increased from 623 to 723 K, there appeared both large polygonal faceted and small circular shapes cavities where previously only smaller circular cavities existed.…”

Helium and Hydrogen Effects in Structural Materials for Nuclear Applications

“…In recent decades, a number of studies [174][175][176][177][178][179][180][181][182][183][184][185][186][187][188][189][190] have been carried out within the framework of synergistic effects between radiation damage and transmutation gas production, but their results are not always consistent. The increase in swelling due to He-H synergistic effects had been demonstrated in the earliest investigations conducted by Farrell and Lee [174] using dual beam (Fe + He) and triple beam (Fe + He + D) irradiation of Fe10.5Cr6Mo ferritic/martensitic steel to 100 dpa and a gas co-implantation level of 40 appm D/dpa and 10 appm He/dpa at 500 °C.…”

Effect of Damage Rate on the Cavity Swelling of Pure Nickel Irradiated with Triple Ion Beams

“…MSIB irradiation has been used for many years to study the He-H synergistic effects on cavity behavior and the swelling of materials. Many results have shown that swelling was significantly enhanced, even up to a hundred times [15,16]. These results raised concerns about the performance of materials in the fusion reactor environment, however, they were also questioned due to the high damage rates of MSIB experiments.…”