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Radiation Damage in Materials: Helium Effects

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A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (1 July 2019) | Viewed by 46095

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Dr. Yongqiang Wang

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Guest Editor

Materials Science & Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87544, USA
Interests: Ion enhanced synthesis; ion implantation; radiation damage; irradiated materials; thin films; surface characterization; complex oxides; nuclear materials
Special Issues, Collections and Topics in MDPI journals

Dr. Khalid Hattar

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Guest Editor

Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, NM 87185, USA
Interests: in situ transmission electron microscopy (TEM); ion beam modification (IBM); extreme environments; in situ scanning electron microscopy (SEM); nanostructure stability
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Special Issue Information

Dear Colleagues,

Understanding radiation damage effects in materials, used in various irradiation environments, has been an ongoing challenge for several decades. The complexity stems from the fundamental particle–solid interactions involving both spatial and temporal length scales and the damage recovery dynamics after the collision cascades. Adding to this complexity are the transmuted impurities that are unavoidable from accompanying nuclear processes, such as (neutron, alpha) reactions and their interactions with both intrinsic and extrinsic defects through damage recovery and defects evolution processes.

Helium is one such impurity that plays an important and unique role in controlling the microstructure and properties of materials due to its virtually zero solubility in any material systems. The ultra-low solubility forces He atoms self-precipitate into small He bubbles that become nucleation sites for further voids growth under radiation induced vacancy supersaturations, resulting in material swelling and high temperature He embrittlement, as well as surface blistering under low energy and high flux He bombardment.

This Special Issue, “Radiation Damage in Materials—Helium Effects”, invites review articles and full length papers on new irradiation material research activities and novel material ideas that focus on understanding He effects on microstructure evolution and thermo-mechanical properties using experimental and/or modeling approaches, where material systems include, but are not limited to, advanced structural steels for fast fission and fusion applications, and plasma facing materials, such as tungsten in fusion devices. Research related to self-irradiation damage by energetic alpha emissions in actinides, as well as in advanced nuclear waste materials, are also encouraged.

Dr. Yongqiang Wang
Dr. Khalid Hattar
Guest Editors

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Keywords

radiation damage
helium bubbles
ion irradiation
nuclear materials

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Published Papers (13 papers)

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Editorial

Jump to: Research, Review, Other

4 pages, 173 KiB

Open AccessEditorial

Special Issue: Radiation Damage in Materials—Helium Effects

by Yongqiang Wang and Khalid Hattar

Materials 2020, 13(9), 2143; https://doi.org/10.3390/ma13092143 - 6 May 2020

Cited by 4 | Viewed by 2425

Abstract

Despite its scarcity in terrestrial life, helium effects on microstructure evolution and thermo-mechanical properties can have a significant impact on the operation and lifetime of applications, including: advanced structural steels in fast fission reactors, plasma facing and structural materials in fusion devices, spallation neutron target designs, energetic alpha emissions in actinides, helium precipitation in tritium-containing materials, and nuclear waste materials. The small size of a helium atom combined with its near insolubility in almost every solid makes the helium–solid interaction extremely complex over multiple length and time scales. This Special Issue, “Radiation Damage in Materials—Helium Effects”, contains review articles and full-length papers on new irradiation material research activities and novel material ideas using experimental and/or modeling approaches. These studies elucidate the interactions of helium with various extreme environments and tailored nanostructures, as well as their impact on microstructural evolution and material properties. Full article

(This article belongs to the Special Issue Radiation Damage in Materials: Helium Effects)

Research

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11 pages, 19477 KiB

Open AccessArticle

The Role of Helium on Ejecta Production in Copper

by Saryu Fensin, David Jones, Daniel Martinez, Calvin Lear and Jeremy Payton

Materials 2020, 13(6), 1270; https://doi.org/10.3390/ma13061270 - 11 Mar 2020

Cited by 10 | Viewed by 2343

Abstract

The effect of helium (He) concentration on ejecta production in OFHC-Copper was investigated using Richtmyer–Meshkov Instability (RMI) experiments. The experiments involved complex samples with periodic surface perturbations machined onto the surface. Each of the four target was implanted with a unique helium concentration [...] Read more.

λ \approx 65 μ

m, and their amplitudes

h_{0}

were varied to determine the wavenumber

(2 π / λ)

amplitude product

k h_{0}

at which ejecta production beganfor Cu with and without He. The velocity and mass of the ejecta produced was quantified using Photon Doppler Velocimetry (PDV) and Lithium-Niobate (LN) pins, respectively. Our results show that there was an increase of 30% in the velocity at which the ejecta cloud was traveling in Copper with 4000 appm as compared to its unimplanted counterpart. Our work also shows that there was a finer cloud of ejecta particles that was not detected by the PDV probes but was detected by the early arrival of a “signal” at the LN pins. While the LN pins were not able to successfully quantify the mass produced due to it being in the solid state, they did provide information on timing. Our results show that ejecta was produced for a longer time in the 4000 appm copper. Full article

(This article belongs to the Special Issue Radiation Damage in Materials: Helium Effects)

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10 pages, 2701 KiB

Open AccessCommunication

In-Situ Helium Implantation and TEM Investigation of Radiation Tolerance to Helium Bubble Damage in Equiaxed Nanocrystalline Tungsten and Ultrafine Tungsten-TiC Alloy

by Osman El Atwani, Kaan Unal, William Streit Cunningham, Saryu Fensin, Jonathan Hinks, Graeme Greaves and Stuart Maloy

Materials 2020, 13(3), 794; https://doi.org/10.3390/ma13030794 - 10 Feb 2020

Cited by 12 | Viewed by 3103

Abstract

The use of ultrafine and nanocrystalline materials is a proposed pathway to mitigate irradiation damage in nuclear fusion components. Here, we examine the radiation tolerance of helium bubble formation in 85 nm (average grain size) nanocrystalline-equiaxed-grained tungsten and an ultrafine tungsten-TiC alloy under extreme low energy helium implantation at 1223 K via in-situ transmission electron microscope (TEM). Helium bubble damage evolution in terms of number density, size, and total volume contribution to grain matrices has been determined as a function of He⁺ implantation fluence. The outputs were compared to previously published results on severe plastically deformed (SPD) tungsten implanted under the same conditions. Large helium bubbles were formed on the grain boundaries and helium bubble damage evolution profiles are shown to differ among the different materials with less overall damage in the nanocrystalline tungsten. Compared to previous works, the results in this work indicate that the nanocrystalline tungsten should possess a fuzz formation threshold more than one order of magnitude higher than coarse-grained tungsten. Full article

(This article belongs to the Special Issue Radiation Damage in Materials: Helium Effects)

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14 pages, 4131 KiB

Open AccessArticle

Effect of Helium on Dispersoid Evolution under Self-Ion Irradiation in A Dual-Phase 12Cr Oxide-Dispersion-Strengthened Alloy

by Hyosim Kim, Tianyao Wang, Jonathan G. Gigax, Shigeharu Ukai, Frank A. Garner and Lin Shao

Materials 2019, 12(20), 3343; https://doi.org/10.3390/ma12203343 - 14 Oct 2019

Cited by 3 | Viewed by 2075

Abstract

As one candidate alloy for future Generation IV and fusion reactors, a dual-phase 12Cr oxide-dispersion-strengthened (ODS) alloy was developed for high temperature strength and creep resistance and has shown good void swelling resistance under high damage self-ion irradiation at high temperature. However, the effect of helium and its combination with radiation damage on oxide dispersoid stability needs to be investigated. In this study, 120 keV energy helium was preloaded into specimens at doses of 1 × 10¹⁵ and 1 × 10¹⁶ ions/cm² at room temperature, and 3.5 MeV Fe self-ions were sequentially implanted to reach 100 peak displacement-per-atom at 475 °C. He implantation alone in the control sample did not affect the dispersoid morphology. After Fe ion irradiation, a dramatic increase in density of coherent oxide dispersoids was observed at low He dose, but no such increase was observed at high He dose. The study suggests that helium bubbles act as sinks for nucleation of coherent oxide dispersoids, but dispersoid growth may become difficult if too many sinks are introduced, suggesting that a critical mass of trapping is required for stable dispersoid growth. Full article

(This article belongs to the Special Issue Radiation Damage in Materials: Helium Effects)

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16 pages, 4835 KiB

Open AccessArticle

Swelling and Helium Bubble Morphology in a Cryogenically Treated FeCrNi Alloy with Martensitic Transformation and Reversion after Helium Implantation

by Feifei Zhang, Lynn Boatner, Yanwen Zhang, Di Chen, Yongqiang Wang and Lumin Wang

Materials 2019, 12(17), 2821; https://doi.org/10.3390/ma12172821 - 2 Sep 2019

Cited by 9 | Viewed by 3663

Abstract

A cryo-quenched 70 wt % Fe-15 wt% Cr-15 wt% Ni single-crystal alloy with fcc (face centered cubic), bcc (body centered cubic), and hcp (hexagonal close packed) phases was implanted with 200 keV He⁺ ions up to 2 × 10¹⁷ ions·cm⁻² at 773 K. Surface-relief features were observed subsequent to the He⁺ ion implantation, and transmission electron microscopy was used to characterize both the surface relief properties and the details of associated “swelling effects” arising cumulatively from the austenitic-to-martensitic phase transformation and helium ion-induced bubble evolution in the single-crystal ternary alloy. The bubble size in the bcc phase was found to be larger than that in the fcc phase, while the bubble density in the bcc phase was correspondingly lower. The phase boundaries with misfit dislocations formed during the martensitic transformation and reversion processes served as helium traps that dispersed the helium bubble distribution. Swelling caused by the phase transformation in the alloy was dominant compared to that caused by helium bubble formation due to the limited depth of the helium ion implantation. The detailed morphology of helium bubbles formed in the bcc, hcp, and fcc phases were compared and correlated with the characters of each phase. The helium diffusion coefficient under irradiation at 773 K in the bcc phase was much higher (i.e., by several orders of magnitude) than that in the fcc phase and led to faster bubble growth. Moreover, the misfit phase boundaries were shown to be effective sites for the diffusion of helium atoms. This feature may be considered to be a desirable property for improving the radiation tolerance of the subject, ternary alloy. Full article

(This article belongs to the Special Issue Radiation Damage in Materials: Helium Effects)

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14 pages, 6603 KiB

Open AccessFeature PaperArticle

Dual Beam In Situ Radiation Studies of Nanocrystalline Cu

by Cuncai Fan, Zhongxia Shang, Tongjun Niu, Jin Li, Haiyan Wang and Xinghang Zhang

Materials 2019, 12(17), 2721; https://doi.org/10.3390/ma12172721 - 25 Aug 2019

Cited by 14 | Viewed by 3142

Abstract

Nanocrystalline metals have shown enhanced radiation tolerance as grain boundaries serve as effective defect sinks for removing radiation-induced defects. However, the thermal and radiation stability of nanograins are of concerns since radiation may induce grain boundary migration and grain coarsening in nanocrystalline metals when the grain size falls in the range of several to tens of nanometers. In addition, prior in situ radiation studies on nanocrystalline metals have focused primarily on single heavy ion beam radiations, with little consideration of the helium effect on damage evolution. In this work, we utilized in situ single-beam (1 MeV Kr⁺⁺) and dual-beam (1 MeV Kr⁺⁺ and 12 keV He⁺) irradiations to investigate the influence of helium on the radiation response and grain coarsening in nanocrystalline Cu at 300 °C. The grain size, orientation, and individual grain boundary character were quantitatively examined before and after irradiations. Statistic results suggest that helium bubbles at grain boundaries and grain interiors may retard the grain coarsening. These findings provide new perspective on the radiation response of nanocrystalline metals. Full article

(This article belongs to the Special Issue Radiation Damage in Materials: Helium Effects)

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9 pages, 2209 KiB

Open AccessCommunication

Investigating Helium Bubble Nucleation and Growth through Simultaneous In-Situ Cryogenic, Ion Implantation, and Environmental Transmission Electron Microscopy

by Caitlin A. Taylor, Samuel Briggs, Graeme Greaves, Anthony Monterrosa, Emily Aradi, Joshua D. Sugar, David B. Robinson, Khalid Hattar and Jonathan A. Hinks

Materials 2019, 12(16), 2618; https://doi.org/10.3390/ma12162618 - 16 Aug 2019

Cited by 8 | Viewed by 3305

Abstract

Palladium can readily dissociate molecular hydrogen at its surface, and rapidly accept it onto the octahedral sites of its face-centered cubic crystal structure. This can include radioactive tritium. As tritium β-decays with a half-life of 12.3 years, He-3 is generated in the metal lattice, causing significant degradation of the material. Helium bubble evolution at high concentrations can result in blister formation or exfoliation and must therefore be well understood to predict the longevity of materials that absorb tritium. A hydrogen over-pressure must be applied to palladium hydride to prevent hydrogen from desorbing from the metal, making it difficult to study tritium in palladium by methods that involve vacuum, such as electron microscopy. Recent improvements in in-situ ion implantation Transmission Electron Microscopy (TEM) allow for the direct observation of He bubble nucleation and growth in materials. In this work, we present results from preliminary experiments using the new ion implantation Environmental TEM (ETEM) at the University of Huddersfield to observe He bubble nucleation and growth, in-situ, in palladium at cryogenic temperatures in a hydrogen environment. After the initial nucleation phase, bubble diameter remained constant throughout the implantation, but bubble density increased with implantation time. β-phase palladium hydride was not observed to form during the experiments, likely indicating that the cryogenic implantation temperature played a dominating role in the bubble nucleation and growth behavior. Full article

(This article belongs to the Special Issue Radiation Damage in Materials: Helium Effects)

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9 pages, 2434 KiB

Open AccessFeature PaperCommunication

Resistance to Helium Bubble Formation in Amorphous SiOC/Crystalline Fe Nanocomposite

by Qing Su, Tianyao Wang, Jonathan Gigax, Lin Shao and Michael Nastasi

Materials 2019, 12(1), 93; https://doi.org/10.3390/ma12010093 - 28 Dec 2018

Cited by 8 | Viewed by 3386

Abstract

The management of radiation defects and insoluble He atoms represent key challenges for structural materials in existing fission reactors and advanced reactor systems. To examine how crystalline/amorphous interface, together with the amorphous constituents affects radiation tolerance and He management, we studied helium bubble formation in helium ion implanted amorphous silicon oxycarbide (SiOC) and crystalline Fe composites by transmission electron microscopy (TEM). The SiOC/Fe composites were grown via magnetron sputtering with controlled length scale on a surface oxidized Si (100) substrate. These composites were subjected to 50 keV He+ implantation with ion doses chosen to produce a 5 at% peak He concentration. TEM characterization shows no sign of helium bubbles in SiOC layers nor an indication of secondary phase formation after irradiation. Compared to pure Fe films, helium bubble density in Fe layers of SiOC/Fe composite is less and it decreases as the amorphous/crystalline SiOC/Fe interface density increases. Our findings suggest that the crystalline/amorphous interface can help to mitigate helium defect generated during implantation, and therefore enhance the resistance to helium bubble formation. Full article

(This article belongs to the Special Issue Radiation Damage in Materials: Helium Effects)

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13 pages, 14678 KiB

Open AccessArticle

Simulation Study of Helium Effect on the Microstructure of Nanocrystalline Body-Centered Cubic Iron

by Chunping Xu and Wenjun Wang

Materials 2019, 12(1), 91; https://doi.org/10.3390/ma12010091 - 28 Dec 2018

Cited by 6 | Viewed by 3245

Abstract

Helium (He) effect on the microstructure of nanocrystalline body-centered cubic iron (BCC-Fe) was studied through Molecular Dynamics (MD) simulation and simulated X-ray Diffraction (XRD). The crack generation and the change of lattice constant were investigated under a uniaxial tensile strain at room temperature to explore the roles of He concentration and distribution played in the degradation of mechanical properties. The simulation results show that the expansion of the lattice constant decreases and the swelling rate increases while the He in the BCC region diffuses into the grain boundary (GB) region. The mechanical property of nanocrystalline BCC-Fe shows He concentration and distribution dependence, and the existence of He in GB is found to benefit the generation and growth of cracks and to affect the strength of GB during loading. It is observed that the reduction of tensile stress contributed by GB He is more obvious than that contributed by grain interior He. Full article

(This article belongs to the Special Issue Radiation Damage in Materials: Helium Effects)

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Review

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22 pages, 8686 KiB

Open AccessReview

Interface Effects on He Ion Irradiation in Nanostructured Materials

by Wenfan Yang, Jingyu Pang, Shijian Zheng, Jian Wang, Xinghang Zhang and Xiuliang Ma

Materials 2019, 12(16), 2639; https://doi.org/10.3390/ma12162639 - 19 Aug 2019

Cited by 19 | Viewed by 3594

Abstract

In advanced fission and fusion reactors, structural materials suffer from high dose irradiation by energetic particles and are subject to severe microstructure damage. He atoms, as a byproduct of the (n, α) transmutation reaction, could accumulate to form deleterious cavities, which accelerate radiation-induced embrittlement, swelling and surface deterioration, ultimately degrade the service lifetime of reactor materials. Extensive studies have been performed to explore the strategies that can mitigate He ion irradiation damage. Recently, nanostructured materials have received broad attention because they contain abundant interfaces that are efficient sinks for radiation-induced defects. In this review, we summarize and analyze the current understandings on interface effects on He ion irradiation in nanostructured materials. Some key challenges and research directions are highlighted for studying the interface effects on radiation damage in nanostructured materials. Full article

(This article belongs to the Special Issue Radiation Damage in Materials: Helium Effects)

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19 pages, 14492 KiB

Open AccessFeature PaperReview

An Overview of Recent Standard and Accelerated Molecular Dynamics Simulations of Helium Behavior in Tungsten

by Luis Sandoval, Danny Perez, Blas P. Uberuaga and Arthur F. Voter

Materials 2019, 12(16), 2500; https://doi.org/10.3390/ma12162500 - 7 Aug 2019

Cited by 9 | Viewed by 3231

Abstract

One of the most critical challenges for the successful adoption of nuclear fusion power corresponds to plasma-facing materials. Due to its favorable properties in this context (low sputtering yield, high thermal conductivity, high melting point, among others), tungsten is a leading candidate material. Nevertheless, tungsten is affected by the plasma and fusion byproducts. Irradiation by helium nuclei, in particular, strongly modifies the surface structure by a synergy of processes, whose origin is the nucleation and growth of helium bubbles. In this review, we present recent advances in the understanding of helium effects in tungsten from a simulational approach based on accelerated molecular dynamics, which emphasizes the use of realistic parameters, as are expected in experimental and operational fusion power conditions. Full article

(This article belongs to the Special Issue Radiation Damage in Materials: Helium Effects)

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32 pages, 11450 KiB

Open AccessReview

Radiation-Induced Helium Bubbles in Metals

by Shi-Hao Li, Jing-Ting Li and Wei-Zhong Han

Materials 2019, 12(7), 1036; https://doi.org/10.3390/ma12071036 - 28 Mar 2019

Cited by 94 | Viewed by 7983

Abstract

Helium (He) bubbles are typical radiation defects in structural materials in nuclear reactors after high dose energetic particle irradiation. In the past decades, extensive studies have been conducted to explore the dynamic evolution of He bubbles under various conditions and to investigate He-induced hardening and embrittlement. In this review, we summarize the current understanding of the behavior of He bubbles in metals; overview the mechanisms of He bubble nucleation, growth, and coarsening; introduce the latest methods of He control by using interfaces in nanocrystalline metals and metallic multilayers; analyze the effects of He bubbles on strength and ductility of metals; and point out some remaining questions related to He bubbles that are crucial for design of advanced radiation-tolerant materials. Full article

(This article belongs to the Special Issue Radiation Damage in Materials: Helium Effects)

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Other

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7 pages, 1642 KiB

Open AccessLetter

Comparison of Vacancy Sink Efficiency of Cu/V and Cu/Nb Interfaces by the Shared Cu Layer

by Huaqiang Chen, Jinlong Du, Yanxia Liang, Peipei Wang, Jinchi Huang, Jian Zhang, Yunbiao Zhao, Xingjun Wang, Xianfeng Zhang, Yuehui Wang, George A. Stanciu and Engang Fu

Materials 2019, 12(16), 2628; https://doi.org/10.3390/ma12162628 - 18 Aug 2019

Cited by 3 | Viewed by 2956

Abstract

This paper provides a new method to compare and then reveal the vacancy sink efficiencies quantitively between different hetero-interfaces with a shared Cu layer in one sample, in contrast to previous studies, which have compared the vacancy sink efficiencies of interfaces in different samples. Cu-Nb-Cu-V nanoscale metallic multilayer composites (NMMCs) containing Cu/V and Cu/Nb interfaces periodically were prepared as research samples and bombarded with helium ions to create vacancies which were filled by helium bubbles. A special Cu layer shared by adjoining Cu/V and Cu/Nb interfaces exists, in which the implanted helium concentration reaches its maximum and remains nearly constant with a well-designed incident energy. The results show that bubble-denuded zones (BDZ) close to interfaces exist, and that the width of the BDZ close to the Cu/V interface is less than that of Cu/Nb interface. This result is explained by one-dimensional diffusion theory, and the ratio of vacancy sink efficiency between Cu/V and Cu/Nb interfaces is calculated. Conclusively, Cu/Nb interfaces are more efficient than Cu/V interfaces in eliminating vacancies induced by radiation. Full article

(This article belongs to the Special Issue Radiation Damage in Materials: Helium Effects)

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