Compression of self-ion implanted iron micropillars

Grieveson, Eleanor M.; Armstrong, David E.J.; Xu, Shuo; Roberts, Steve

doi:10.1016/j.jnucmat.2012.06.014

Cited by 43 publications

(14 citation statements)

References 40 publications

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“…Position annihilation spectroscopy 19 and thermal desorption spectroscopy 23 would also allow study of location of the helium in greater detail-complementing the TEM already performed and allowing a greater understanding of the formation and growth of helium clusters and bubbles. For further evaluation of the effects of helium on mechanical properties other than hardness such as yield stress and fracture behaviour advanced micromechanical testing using focused ion beam machined pillars 24,25 and microcantilers [26][27][28] are being employed. However, undoubtedly these dramatic hardness increases resulting from helium implantation into tungsten represent a particular concern for the application of tungsten, which is already inherently brittle, in fusion reactor environments.…”

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confidence: 99%

Effects of sequential tungsten and helium ion implantation on nano-indentation hardness of tungsten

Armstrong¹,

Edmondson²,

Roberts³

2013

Applied Physics Letters

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To simulate neutron and helium damage in a fusion reactor first wall sequential self-ion implantation up to 13 dpa followed by helium-ion implantation up to 3000 appm was performed to produce damaged layers of $2 lm depth in pure tungsten. The hardness of these layers was measured using nanoindentation and was studied using transmission electron microscopy. Substantial hardness increases were seen in helium implanted regions, with smaller hardness increases in regions which had already been self-ion implanted, thus, containing pre-existing dislocation loops. This suggests that, for the same helium content, helium trapped in distributed vacancies gives stronger hardening than helium trapped in vacancies condensed into dislocation loops. V C 2013 AIP Publishing LLC. [http://dx.Tungsten is the most important candidate material for plasma facing surfaces in any future nuclear fusion power device, 1 due to its combination of low sputtering rate, low activation under transmutation, and good thermal conductivity. 2 In a plasma-facing role, it will be subjected to some of the most extreme conditions of any engineering materials; surface temperatures of over 1000 C, damage levels of up to 50 dpa/yr from 14.1 MeV neutrons, transmutation-induced compositional changes of up to 5 at. % over operational lifetimes 3 and implantation of helium directly from the plasma. 4 Degradation of tungsten in these conditions will limit the component lifetime and have adverse effects on the fusion plasma efficiency due to ingress of sputtered tungsten atoms and dust. The combination of displacement damage from neutrons and helium (present due to both transmutation and injection from the plasma) will result in significant mechanical changes in the tungsten. Understanding the mechanisms behind these effects will be vital in modelling failure mechanisms of plasma-facing tungsten. Studies of helium in tungsten have concentrated on the mechanisms behind the formation of bubbles, 5 voids, 6 and "nano-fuzz"; 7 however, very little work has been carried out to assess the influence of helium on tungsten's mechanical properties.Nanoindentation has been used to study the effects of helium implantation on the mechanical properties of advanced nuclear steels. Chen et al. 8 performed simultaneous and sequential Fe þ ion and He þ ion implantations into a PM2000 ODS steel (in the as-received state and cold-rolled to 30% and 70% reduction in thickness), to 31 dpa and 18 appm/dpa of helium. They saw a hardness increase due to the implantation of 1.15 GPa in the as-received material, 0.23 GPa in the 30% rolled, and 0.2 GPa for the 70% rolled. For the two rolled materials, hardness increases were within 1 standard deviation of the unirradiated hardness. This suggests that the rolling produces defects which act as sinks for helium and displacement damage and which reduce their hardening effect. Kogler et al. 9 also carried out Fe/He implantations on PM2000, in as-received and heat-treated conditions, performing both sequential and simultaneous implantations to ...

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confidence: 99%

Effects of sequential tungsten and helium ion implantation on nano-indentation hardness of tungsten

Armstrong¹,

Edmondson²,

Roberts³

2013

Applied Physics Letters

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“…35 In order to enhance the data acquired from nanoindentation, it is possible to carry out micro-pillar or microcantilever tests. 33,36 These forms of testing provide additional information regarding plastic deformation and fracture mechanics (see Fig. 6).…”

Section: Micromechanicsmentioning

confidence: 99%

Predicting the performance of tungsten in a fusion environment: a literature review

Abernethy

2016

Materials Science and Technology

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Tungsten has been proposed for use in the divertor of future fusion devices. In this environment, it will be exposed to high heat fluxes, neutron damage and hydrogen and helium implantation. This review covers previous experimental and modelling work to establish our ability to predict the performance of tungsten in a fusion environment. Surrogates for high-energy neutrons have been used to predict the change in mechanical properties of tungsten, including fission neutron and self-ion exposure. These studies are critically analysed, with a focus on the difference in results from neutron and ion studies. Further studies to improve our ability to predict the performance of tungsten are proposed as a critical part of the path towards a working fusion reactor.

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“…Recently, considerable efforts have been dedicated to micromechanical testing of small scale specimens whose microstructure can be characterized by various advanced techniques such as scanning electron microscopy [1], high resolution transmission electron microscopy [2], atom probe tomography [3], and X-ray nano-tomography [4]. This is because such small-scale tests can be ion implanted or neutron irradiated but still handled in laboratory conditions due to their small volume even if the samples show low to medium levels of activity.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of micro-scale fracture specimens for nuclear applications by direct laser writing

et al. 2018

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Compression of self-ion implanted iron micropillars

Cited by 43 publications

References 40 publications

Effects of sequential tungsten and helium ion implantation on nano-indentation hardness of tungsten

Effects of sequential tungsten and helium ion implantation on nano-indentation hardness of tungsten

Predicting the performance of tungsten in a fusion environment: a literature review

Fabrication of micro-scale fracture specimens for nuclear applications by direct laser writing

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