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UKAEA-CCFE-PR(19)222019
A viable fusion power station is reliant on the development of plasma facing materials that can withstand the combined effects of high temperature operation and high neutron doses. In this study we focus on W, the most promising candidate material. Re is the primary transmutation product and has been shown to induce embrittlement through cluster fo…
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UKAEA-CCFE-PR(18)772018
A novel W-based refractory high entropy alloy with outstanding radiation resistance has been developed. The alloy was grown as thin films showing a bimodal grain size distribution in the nanocrystalline and ultrafine regimes and a unique 4 nm lamella-like structure revealed by atom probe tomography (APT). Transmission electron microscopy (TEM) and …
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CCFE-PR(17)642017
In a fusion tokamak, the plasma of hydrogen isotopes is in contact with tungsten at the surface of a divertor. In the bulk of the material, the hydrogen concentration profile tends towards dynamic equilibrium between the flux of incident ions and their trapping and release from defects, either native or produced by ion and neutron irradiation. The …
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CCFE-PR(17)712017
We present an empirical interatomic potential for tungsten, particularly well suited for simulations of vacancy-type defects. We compare energies and structures of vacancy clusters generated with the empirical potential with an extensive new database of values computed using density functional theory, and show that the new potential predicts low-en…
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2017
The structural and magnetic properties of CoCrFeyNi and CoCrFeNi-Pdx alloys earlier investigated experimentally by x-ray and neutron diffraction techniques and magnetometry have been theoretically reproduced using two complementary approaches for electronic structure calculations, i.e. the Korringa–Kohn–Rostoker method with the coherent potenti…
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CCFE-PR(17)552017
High Entropy Alloys (HEAs) is a fascinating field of research, with an increasing number of new alloys discovered. This would hardly be conceivable without the aid of materials modeling and the computational alloy design to investigate the immense compositional space. The simplicity of the microstructure achieved contrasts with the enormous complex…
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CCFE-PR(17)062017
Using an ab initio approach, we explore the stability of small vacancy and vacancychromium clusters in dilute body-centred cubic Fe-Cr alloys. To explain experimental observations described in C.D. Hardie et al., J. Nucl. Mater. 439, 33 (2013) and showing the occurrence of Cr segregation in low-Cr alloys, we investigate if chromium can form stable …
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CCFE-PR(17)452017
Helium bubble production in tungsten has been studied combining transmission electron microscopy and in situ irradiations with 10 keV He+ ions. The irradiations were carried out at four temperatures (773 K, 1073 K, 1273 K, 1473 K), and were held at intervals of (0.45; 0.9; 1.2; 1.5) × 1020 He+/m2 for each temperature. Based on detailed analyses of…
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CCFE-PR(17)572017
Quantum dynamics within solids is usually restricted to low mass particles such as electrons and muons, or single atoms of light elements such as hydrogen. In this letter we report observation of the quantum-assisted motion of self-interstitial atom clusters in tungsten (each of mass 184 Da), travelling distances of several nanometres between trapp…
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CCFE-PR(17)612017
The vacancies produced in high energy collision cascades can form in irradiated tungsten vacancy clusters or vacancy prismatic dislocation loops. Moreover, vacancy loop can easily transform to a planar vacancy cluster. We investigated the formation energies of these three types of vacancy defects as a function of number of vacancies using three EAM…
Showing 41 - 50 of 86 UKAEA Paper Results