Characterization of helium ion implanted reduced activation ferritic/martensitic steel with positron annihilation and helium thermal desorption methods

Carvalho, Isabel; Schüt, H.; Fedorov, Alexander; Luzginova, N.V.; Sietsma, Jilt

doi:10.1016/j.jnucmat.2013.03.029

Cited by 9 publications

(3 citation statements)

References 5 publications

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“…The W parameter corresponds to positron annihilation with the core electron and is more sensitive to the chemical surrounding at the annihilation site. Due to the low electron density, the probability of the positrons annihilation with low‐momentum electrons will be enhanced when positrons are trapped by an open volume defect 24 . Consequently, the increase of the S parameter and the decrease of W parameter indicates the presence of open volume defects.…”

Section: Methodsmentioning

confidence: 99%

Helium behavior and vacancy‐defect evolution in nickel‐base alloy by helium ion beam irradiation and annealing

Zhu

Shen

et al. 2022

Surface & Interface Analysis

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Nickel‐base alloys have been selected as a potential metallic material for reactor internals in Generation IV reactors. In order to evaluate their helium embrittlement resistance, microstrain changes and evolution of vacancy‐type defects after Helium irradiation and postimplantation annealing have been studied by grazing incidence X‐ray diffraction (GIXRD) and slow positron doppler broadening spectroscopy (PDB). GIXRD results show that the increase in microstrain after helium irradiation is more pronounced at high doses. The observed S parameters of PDB increase with the irradiation doses, which indicates a significant number of vacancy‐type defects, possibly helium‐vacancy clusters. For postimplantation annealing specimens, the microstrain characterized by GIXRD has recovered. The surprise is the S parameters that significantly increase, revealing that helium atoms trapped at unstable helium‐vacancy clusters desorb during annealing, contributing to the growth of helium bubbles. These findings of microstrain mechanisms and vacancy‐type defects behaviors give us new insights into the helium irradiation evaluation.

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Section: Methodsmentioning

confidence: 99%

Helium behavior and vacancy‐defect evolution in nickel‐base alloy by helium ion beam irradiation and annealing

Zhu

Shen

et al. 2022

Surface & Interface Analysis

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“…[17,18] Therefore, thermal desorption spectropy (TDS) can analyze helium bubbles with small size, and each characteristic peak may represent a different desorption process. [19,20] Supplementary to conventional mechanical measurements, now it is the simplest, most practical, and indirect method to study the behavior of helium and their defects (a single atom, and bubbles). [21] In the present studies, a nickel alloy, has been chosen to investigate the helium damage and desorption.…”

Section: Introductionmentioning

confidence: 99%

Thermal desorption characteristic of helium ion irradiated nickel-base alloy*

Zhu

Zhao

et al. 2020

Chinese Phys. B

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The nickel-base alloy is one of the leading candidate materials for generation IV nuclear reactor pressure vessel. To evaluate its stability of helium damage and retention, helium ions with different energy of 80 keV and 180 keV were introduced by ion implantation to a certain dose (peak displacement damage 1–10 dpa). Then thermal desorption spectroscopy (TDS) of helium atoms was performed to discuss the helium desorption characteristic and trapping sites. The desorption peaks shift to a lower temperature with increasing dpa for both 80 keV and 180 keV irradiation, reflecting the reduced diffusion activation energy and faster diffusion within the alloy. The main release peak temperature of 180 keV helium injection is relatively higher than that of 80 keV at the same influence, which is because the irradiation damage of 180 keV, helium formation and entrapment occur deeper. The broadening of the spectra corresponds to different helium trapping sites (He–vacancies, grain boundary) and desorption mechanisms (different He n V m size). The helium retention amount of 80 keV is lower than that of 180 keV, and a saturation limit associated with the irradiation of 80 keV has been reached. The relatively low helium retention proves the better resistance to helium bubbles formation and helium brittleness.

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“…Therefore, in order to understand how temperature affects the evolution of cavities for a given time, an annealing treatment has been applied at 450 °C for 100 h in EUROFER97 and EU-ODS EUROFER steels. He desorption experiments with EUROFER97 [9,10] showed that in a temperature range above 450 °C, the dissociation and diffusion phenomena begin to be critical, so to be able to understand the nucleation and growth of He bubbles, it is necessary to evaluate the mechanisms that govern the diffusion of the He atoms prevailing when the implanted materials are undergoing an annealing process, and to try to find a model to frame that behavior. There are different diffusion mechanisms [11] and its relevance depends on factors such as the nature of the He defect, the annealing temperature, and defects present in the material.…”

Section: Introductionmentioning

confidence: 99%

Nanoindentation and TEM to Study the Cavity Fate after Post-Irradiation Annealing of He Implanted EUROFER97 and EU-ODS EUROFER

et al. 2018

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The effect of post-helium irradiation annealing on bubbles and nanoindentation hardness of two reduced activation ferritic martensitic steels for nuclear fusion applications (EUROFER97 and EU-ODS EUROFER) has been studied. Helium-irradiated EUROFER97 and EU-ODS EUROFER were annealed at 450 °C for 100 h in an argon atmosphere. The samples were tested by nanoindentation and studied by transmission electron microscopy extracting some focused ion beam lamellae containing the whole implanted zone (≈50 µm). A substantial increment in nanoindentation hardness was measured in the area with higher helium content, which was larger in the case of EUROFER97 than in EU-ODS EUROFER. In terms of microstructure defects, while EU-ODS EUROFER showed larger helium bubbles, EUROFER97 experienced the formation of a great population density of them, which means that the mechanism that condition the evolution of cavities for these two materials are different and completely dependent on the microstructure.

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Characterization of helium ion implanted reduced activation ferritic/martensitic steel with positron annihilation and helium thermal desorption methods

Cited by 9 publications

References 5 publications

Helium behavior and vacancy‐defect evolution in nickel‐base alloy by helium ion beam irradiation and annealing

Helium behavior and vacancy‐defect evolution in nickel‐base alloy by helium ion beam irradiation and annealing

Thermal desorption characteristic of helium ion irradiated nickel-base alloy*

Nanoindentation and TEM to Study the Cavity Fate after Post-Irradiation Annealing of He Implanted EUROFER97 and EU-ODS EUROFER

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