Composition and magnetic character of nanometre-size Cu precipitates in reactor pressure vessel steels: Implications for nuclear power plant lifetime extension

Asoka‐Kumar, P.; Wirth, B. D.; Sterne, P. A.; Howell, R.H.; Odette, G.R.

doi:10.1080/0950083021000019958

Cited by 56 publications

(33 citation statements)

References 19 publications

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“…In contrast, results obtained with small-angle neutron scattering ͑SANS͒ ͑Refs. 12-14͒ and positron annihilation [15][16][17] suggest that the precipitates are almost pure Cu with only minor amounts of Fe. Interpretation of the SANS experiments however depends on a priori knowledge of the magnetic state and the atom density of the small Cu clusters, which causes some uncertainty in the determination of the composition of the Cu precipitates in the initial stage of the precipitation process.…”

Section: Introductionmentioning

confidence: 99%

“…The precipitation of copper from supersaturated Fe-Cu alloys has been investigated extensively, both experimentally [4][5][6][7][8][9][10][11][12][13][14][15][16][17] and theoretically. [18][19][20][21] It is now generally accepted that, in the initial stages, fully coherent Cu precipitates inherit the body-centered-cubic ͑bcc͒ structure of the ␣-Fe matrix.…”

Section: Introductionmentioning

confidence: 99%

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Thermally activated precipitation at deformation-induced defects in Fe-Cu and Fe-Cu-B-N alloys studied by positron annihilation spectroscopy

Dijk

Schüt

et al. 2010

Phys. Rev. B

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We have investigated the influence of deformation-induced defects on the isothermal precipitation at 550°C in as-quenched ͑solute-supersaturated͒ and annealed ͑solute-depleted͒ Fe-Cu and Fe-Cu-B-N alloys by positron annihilation spectroscopy and hardness tests. Using the coincidence Doppler broadening technique, the evolution of local environment at the positron annihilation sites ͑open-volume defects, Cu precipitates, and matrix͒ was monitored as a function of the aging time. For all samples, plastic deformation causes a pronounced change in S and W parameters signaling the formation of open-volume defects. For the as-quenched samples, aging results in a sharp decrease in the amount of open-volume defects combined with the rise of a strong copper signature, which can be attributed to preferential copper precipitation at the open-volume defects introduced by plastic deformation. In contrast, the open-volume defects of the annealed samples can only be reduced partially. Both the hardness tests and the positron annihilation spectroscopy indicate that the addition of B and N to the Fe-Cu alloy causes a significant acceleration of the precipitation in the as-quenched alloys.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermally activated precipitation at deformation-induced defects in Fe-Cu and Fe-Cu-B-N alloys studied by positron annihilation spectroscopy

Dijk

Schüt

et al. 2010

Phys. Rev. B

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“…Secondly, the spin-resolved electron momentum density of magnetic NCs can be obtained experimentally using radio-isotope e + sources, which emit partially polarized positrons. This was used by Asoka-Kumar et al [6] to show the non-magnetic behaviour of Cu NCs embedded in ferromagnetic Fe. 6 Conclusion A short overview of positron studies of nanocrystals is presented, illustrated by recent experimental and theoretical advances.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

“…At small sizes, the surface or interface energy becomes a very significant factor in establishing not only the interior crystal structure but also the specific surface structure and ad-atom termination of the NCs. These special properties underlie the large potential of NCs for applications in areas of nanostructured thin-film solar cells [4], opto-electronics [3] and spintronics [5], fission/fusion reactor vessel steels [6], metal hydrides for hydrogen storage [7], and fluorescence-based detection of biomolecules [3].During the last decade, it has been shown that positrons (e + ) act as a sensitive, self-seeking probe of embedded and colloidal NCs [8][9][10][11][12][13][14][15][16][17][18][19][20], revealing the local structural properties and electronic structure via a measurement of the electron momentum density [21]. Positron methods are thus capable of extracting valuable information on properties at specific surface, interface or defect sites in the NCs, which are difficult to access by other methods such as transmission electron microscopy, X-ray diffraction (XRD), and EXAFS.…”

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confidence: 99%

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Positron studies of surfaces, structure and electronic properties of nanocrystals

Eijt

Barbiellini

Houtepen

et al. 2007

Phys. Status Solidi (c)

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A brief review is given of recent positron studies of metal and semiconductor nanocrystals. The prospects offered by positron annihilation as a sensitive method to access nanocrystal (NC) properties are described and compared with other experimental methods. The tunability of the electronic structure of nanocrystals underlies their great potential for application in many areas. Owing to their large surface-to-volume ratio, the surfaces and interfaces of NCs play a crucial role in determining their properties. Here we focus on positron 2D angular correlation of annihilation radiation (2D-ACAR) and (two-detector) Doppler studies for investigating surfaces and electronic properties of CdSe NCs.1 Introduction Nanoscale particles have become extremely important in the tailoring of materials for a wide range of applications [1][2][3]. In particular, semiconductor nanocrystals (NCs) have attracted wide interest because their electronic and optical properties can be tuned by variation of their size and shape [2,3]. At small sizes, the surface or interface energy becomes a very significant factor in establishing not only the interior crystal structure but also the specific surface structure and ad-atom termination of the NCs. These special properties underlie the large potential of NCs for applications in areas of nanostructured thin-film solar cells [4], opto-electronics [3] and spintronics [5], fission/fusion reactor vessel steels [6], metal hydrides for hydrogen storage [7], and fluorescence-based detection of biomolecules [3].During the last decade, it has been shown that positrons (e + ) act as a sensitive, self-seeking probe of embedded and colloidal NCs [8][9][10][11][12][13][14][15][16][17][18][19][20], revealing the local structural properties and electronic structure via a measurement of the electron momentum density [21]. Positron methods are thus capable of extracting valuable information on properties at specific surface, interface or defect sites in the NCs, which are difficult to access by other methods such as transmission electron microscopy, X-ray diffraction (XRD), and EXAFS. Furthermore, insight into the electronic structure of buried or embedded NC systems is gained, which is difficult to obtain with e.g. STM or XPS.

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Positron annihilation study of neutron irradiated pure Fe and Fe‐Cu binary alloys

Lambrecht¹,

Jardin²,

Almazouzi³

2007

Phys. Status Solidi (c)

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The hardening and embrittlement of Reactor Pressure Vessel (RPV) steels is of great concern in the actual nuclear power plant life assessment. This embrittlement is caused by irradiation-induced damage, like vacancies, interstitials, solutes and their clusters. Fe-Cu binary alloys are often used to mimic the behaviour of such steels. Their study allows identifying some of the defects responsible of the hardening, especially when compared to pure iron or C-micro-alloyed iron. Owing to their self-seeking and selective trapping, positrons are used to determine the nature of these defects. Recently, at SCK·CEN, a new Positron Annihilation Spectroscopy (PAS) setup has been built, calibrated and optimized to measure the Coincidence Doppler Broadening (CDB) and Lifetime (LT) of neutron irradiated materials. This set-up has been used to measure the CDB and LT of n-irradiated pure Fe and Fe-Cu alloys. It is found that the clustering of Cu take place at the very early stages of irradiation using the CDB while LT measurement are showing much more vacancy clustering for low Cu alloys than in the higher ones. Increasing the neutron dose up to 1.3 × 10 20 n/m 2 , allows the follow up of the kinetic of Cu and V-clustering especially in Fe-Cu alloys. It is found that both copper and carbon decrease the size of vacancy-cluster, when added to iron.

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Composition and magnetic character of nanometre-size Cu precipitates in reactor pressure vessel steels: Implications for nuclear power plant lifetime extension

Cited by 56 publications

References 19 publications

Thermally activated precipitation at deformation-induced defects in Fe-Cu and Fe-Cu-B-N alloys studied by positron annihilation spectroscopy

Thermally activated precipitation at deformation-induced defects in Fe-Cu and Fe-Cu-B-N alloys studied by positron annihilation spectroscopy

Positron studies of surfaces, structure and electronic properties of nanocrystals

Positron annihilation study of neutron irradiated pure Fe and Fe‐Cu binary alloys

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