Radiation Effects in Steels and Alloys

A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Structural Integrity of Metals".

Deadline for manuscript submissions: closed (31 May 2022) | Viewed by 13504

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Institute of Nuclear and Physical Engineering, Slovak University of Technology in Bratislava, Bratislava, Slovakia
Interests: nuclear power plants; material science; positron annihilation techniques
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Special Issue Information

Dear Colleagues,

Radiation damage in steels and alloys is one of the most important damage mechanisms for design materials of nuclear components or facilities. Different particles (not only neutrons, on which the attention is dominantly focused in the nuclear industry) transfer their energy to atoms, which start to migrate, creating vacancies and different interstitials, being responsible for the formation of defect clusters or various microstructural changes (precipitation, segregations on grain boundaries, phase reactions, etc.). Such initiated nuclear reactions or transmutation can create alpha particle emitters which can lead to helium gas and its accommodation or movements in the material. All these mechanisms can significantly deteriorate materials’ properties and limit the life-time of use. Irradiation with energetic particles (such as neutrons, ions, and electrons) can cause a wide range of effects on materials, starting with the formation of point defects such as self-interstitial atoms (SIAs) and vacancies, defect clusters such as dislocation loops and stacking fault tetrahedra (SFTs), and cavities (voids and gas-filled bubbles). These phenomena have been investigated in the last several decades using different techniques and advanced knowledge in material science to new levels. 

The aim of this Special issue is to preserve and maintain knowledge in this area as well as to extend it with actual results collected at different laboratories in recent years. This is fully in line with the extremely important reliability of material properties and increase of operational safety margin in view of long-term safe operation of nuclear facilities.

Prof. Vladimír Slugeň
Guest Editor

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Keywords

  • material science
  • radiation damage
  • microstructure of steels and alloys
  • neutron embrittlement
  • point defects

Published Papers (6 papers)

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Research

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31 pages, 131547 KiB  
Article
Dislocation Loop Generation Differences between Thin Films and Bulk in EFDA Pure Iron under Self-Ion Irradiation at 20 MeV
by Marcelo Roldán, Fernando José Sánchez, Pilar Fernández, Christophe J. Ortiz, Adrián Gómez-Herrero and David Jiménez Rey
Metals 2021, 11(12), 2000; https://0-doi-org.brum.beds.ac.uk/10.3390/met11122000 - 10 Dec 2021
Cited by 4 | Viewed by 2837
Abstract
In the present investigation, high-energy self-ion irradiation experiments (20 MeV Fe+4) were performed on two types of pure Fe samples to evaluate the formation of dislocation loops as a function of material volume. The choice of model material, namely EFDA pure [...] Read more.
In the present investigation, high-energy self-ion irradiation experiments (20 MeV Fe+4) were performed on two types of pure Fe samples to evaluate the formation of dislocation loops as a function of material volume. The choice of model material, namely EFDA pure Fe, was made to emulate experiments simulated with computational models that study defect evolution. The experimental conditions were an ion fluence of 4.25 and 8.5 × 1015 ions/cm2 and an irradiation temperature of 350 and 450 °C, respectively. First, the ions pass through the samples, which are thin films of less than 100 nm. With this procedure, the formation of the accumulated damage zone, which is the peak where the ions stop, and the injection of interstitials are prevented. As a result, the effect of two free surfaces on defect formation can be studied. In the second type of experiments, the same irradiations were performed on bulk samples to compare the creation of defects in the first 100 nm depth with the microstructure found in the whole thickness of the thin films. Apparent differences were found between the thin foil irradiation and the first 100 nm in bulk specimens in terms of dislocation loops, even with a similar primary knock-on atom (PKA) spectrum. In thin films, the most loops identified in all four experimental conditions were b ±a0<100>{200} type with sizes of hundreds of nm depending on the experimental conditions, similarly to bulk samples where practically no defects were detected. These important results would help validate computational simulations about the evolution of defects in alpha iron thin films irradiated with energetic ions at large doses, which would predict the dislocation nucleation and growth. Full article
(This article belongs to the Special Issue Radiation Effects in Steels and Alloys)
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12 pages, 3877 KiB  
Article
On the Limitations of Positron Annihilation Spectroscopy in the Investigation of Ion-Implanted FeCr Samples
by Vladimir Slugen, Jarmila Degmova, Stanislav Sojak, Martin Petriska, Pavol Noga and Vladimir Krsjak
Metals 2021, 11(11), 1689; https://0-doi-org.brum.beds.ac.uk/10.3390/met11111689 - 23 Oct 2021
Cited by 1 | Viewed by 1785
Abstract
New materials for advanced fission/fusion nuclear facilities must inevitably demonstrate resistance to radiation embrittlement. Thermal and radiation ageing accompanied by stress corrosion cracking are dominant effects that limit the operational condition and safe lifetime of the newest nuclear facilities. To study these phenomena [...] Read more.
New materials for advanced fission/fusion nuclear facilities must inevitably demonstrate resistance to radiation embrittlement. Thermal and radiation ageing accompanied by stress corrosion cracking are dominant effects that limit the operational condition and safe lifetime of the newest nuclear facilities. To study these phenomena and improve the current understanding of various aspects of radiation embrittlement, ion bombardment experiments are widely used as a surrogate for neutron irradiation. While avoiding the induced activity, typical for neutron-irradiated samples, is a clear benefit of the ion implantation, the shallow near-surface region of the modified materials may be a complication to the post-irradiation examination (PIE). However, microstructural defects induced by ion implantation can be effectively investigated using various spectroscopic techniques, including slow-positron beam spectroscopy. This method, typically represented by techniques of positron annihilation lifetime spectroscopy and Doppler broadening spectroscopy, enables a unique depth-profile characterisation of the near-surface region affected by ion bombardment or corrosion degradation. One of the best slow-positron beam facilities is available at the pulsed low-energy positron system (PLEPS), operated at FRM-II reactor in Munich (Germany). Bulk studies (such as high energy ion implantation or neutron irradiation experiments) can be, on the other hand, effectively performed using radioisotope positron sources. In this paper, we outline some basics of the two approaches and provide some recommendations to improve the validity of the positron annihilation spectroscopy (PAS) data obtained on ion-irradiated samples using a conventional 22Na positron source. Full article
(This article belongs to the Special Issue Radiation Effects in Steels and Alloys)
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12 pages, 3095 KiB  
Article
Structural-and-Phase Transformations in Fe-4.10 and 7.25 at.% Mn Alloys under Intensity External Actions
by Vladimir V. Ovchinnikov, Efrem V. Makarov and Natalia V. Gushchina
Metals 2021, 11(11), 1667; https://0-doi-org.brum.beds.ac.uk/10.3390/met11111667 - 20 Oct 2021
Cited by 1 | Viewed by 1139
Abstract
The effect of high-pressure torsion (HPT) (P = 8 GPa, e = 5.9) and irradiation with continuous beams of Ar+ ions with energy E = 15 keV on the atomic structure and phase composition of initially quenched iron alloys with 4.10 [...] Read more.
The effect of high-pressure torsion (HPT) (P = 8 GPa, e = 5.9) and irradiation with continuous beams of Ar+ ions with energy E = 15 keV on the atomic structure and phase composition of initially quenched iron alloys with 4.10 and 7.25 at.% Mn was studied by the method of Mössbauer spectroscopy. The supersaturated α-solid solution of Fe-7.25 at.% Mn, in contrast to the stable Fe-4.10 at.% Mn, which passes into a highly nonequilibrium metastable state as a result of HPT deformation, is transformed under the influence of ion irradiation at an abnormally low temperature of 280 °C into a two-phase α + γ-state with a highly enriched γ-phase (austenite) (38.4 at.% Mn) and a depleted α-solid solution with 5.76 at.% Mn. The rapid processes with the formation of the γ-phase with a concentration of Mn close to the extrapolation estimate using the equilibrium phase diagram are explained by the cascade radiation shaking of the material by post-cascade powerful elastic and shock waves. Cascade radiation shaking plays the role of temperature and opens up the possibility of achieving states close to equilibrium in the absence of thermally activated processes at record low temperatures. Full article
(This article belongs to the Special Issue Radiation Effects in Steels and Alloys)
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25 pages, 10221 KiB  
Article
Radiation Effects in Amorphous Metallic Alloys as Revealed by Mössbauer Spectrometry: Part II. Ion Irradiation
by Marcel B. Miglierini
Metals 2021, 11(8), 1309; https://0-doi-org.brum.beds.ac.uk/10.3390/met11081309 - 18 Aug 2021
Viewed by 1785
Abstract
Due to their excellent magnetic properties, amorphous metallic alloys (AMAs) are considered for the construction of magnetic cores of radio-frequency cavities in accelerators. Here, they might be exposed to ion bombardment. The influence of irradiation by both light and heavy ions featuring low [...] Read more.
Due to their excellent magnetic properties, amorphous metallic alloys (AMAs) are considered for the construction of magnetic cores of radio-frequency cavities in accelerators. Here, they might be exposed to ion bombardment. The influence of irradiation by both light and heavy ions featuring low and high energies, respectively, is followed by the techniques of 57Fe Mössbauer spectrometry. Modifications of surface layers in selected Fe-containing AMAs after ion irradiation are unveiled by detection of conversion electrons and photons of characteristic radiation whereas those in their bulk are derived from standard transmission spectra. Rearrangement of microstructure which favors the formation of magnetically active regions, is observed in surface regions bombarded by light ions. Heavy ions caused pronounced effects in the orientation of net magnetization of the irradiated samples. No measurable impact upon short-range order arrangement was observed. Part I of this paper is devoted to radiation effects in Fe-based AMAs induced by neutron irradiation. Full article
(This article belongs to the Special Issue Radiation Effects in Steels and Alloys)
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18 pages, 3147 KiB  
Article
Radiation Effects in Amorphous Metallic Alloys as Revealed by Mössbauer Spectrometry: Part I. Neutron Irradiation
by Marcel B. Miglierini
Metals 2021, 11(5), 845; https://0-doi-org.brum.beds.ac.uk/10.3390/met11050845 - 20 May 2021
Cited by 4 | Viewed by 2057
Abstract
Iron-based amorphous metallic alloys (AMAs) of several compositions were exposed to neutron irradiation with fluences of up to 1019 n/cm2. These materials exhibit excellent magnetic properties which predetermine them for use in electronic devices operated also in radiation-exposed environments. Response [...] Read more.
Iron-based amorphous metallic alloys (AMAs) of several compositions were exposed to neutron irradiation with fluences of up to 1019 n/cm2. These materials exhibit excellent magnetic properties which predetermine them for use in electronic devices operated also in radiation-exposed environments. Response of the studied AMAs to neutron irradiation is followed by Mössbauer spectrometry which probes the local microstructure. Neutron irradiation leads to rearrangement of constituent atoms, their clustering, and formation of stress centers. The observed modifications of topological short-range order result in changes of spectral parameters including average hyperfine magnetic field, B, standard deviation of the distribution of hyperfine fields, and position of the net magnetic moment. After irradiation, especially differences in B-values develop in two opposite directions. This apparent controversy can be explained by formation of specific atomic pairs with different exchange interactions, which depend on the composition of the samples. Part II of this paper will be devoted to radiation effects caused in Fe-based AMAs by ion irradiation. Full article
(This article belongs to the Special Issue Radiation Effects in Steels and Alloys)
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Review

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12 pages, 2145 KiB  
Review
Radiation Damage of Reactor Pressure Vessel Steels Studied by Positron Annihilation Spectroscopy—A Review
by Vladimír Slugeň, Stanislav Sojak, Werner Egger, Vladimir Krsjak, Jana Simeg Veternikova and Martin Petriska
Metals 2020, 10(10), 1378; https://0-doi-org.brum.beds.ac.uk/10.3390/met10101378 - 16 Oct 2020
Cited by 10 | Viewed by 2707
Abstract
Safe and long term operation of nuclear reactors is one of the most discussed challenges in nuclear power engineering. The radiation degradation of nuclear design materials limits the operational lifetime of all nuclear installations or at least decreases its safety margin. This paper [...] Read more.
Safe and long term operation of nuclear reactors is one of the most discussed challenges in nuclear power engineering. The radiation degradation of nuclear design materials limits the operational lifetime of all nuclear installations or at least decreases its safety margin. This paper is a review of experimental PALS/PLEPS studies of different nuclear reactor pressure vessel (RPV) steels investigated over last twenty years in our laboratories. Positron annihilation lifetime spectroscopy (PALS) via its characteristics (lifetimes of positrons and their intensities) provides useful information about type and density of radiation induced defects. The new results obtained on neutron-irradiated and hydrogen ions implanted German steels were compared to those from the previous studies with the aim to evaluate different processes (neutron flux/fluence, thermal treatment or content of selected alloying elements) to the microstructural changes of neutron irradiated RPV steel specimens. The possibility of substitution of neutron treatment (connected to new defects creation) via hydrogen ions implantation was analyzed as well. The same materials exposed to comparable displacement damage (dpa) introduced by neutrons and accelerated hydrogen ions shown that in the results interpretation the effect of hydrogen as a vacancy-stabilizing gas must be considered, too. This approach could contribute to future studies of nuclear fission/fusion design steels treated by high levels of neutron irradiation. Full article
(This article belongs to the Special Issue Radiation Effects in Steels and Alloys)
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