New oxidation-resistant tungsten alloys for use in the nuclear fusion reactors

Litnovsky, A.; Wegener, T.; Klein, F.; Linsmeier, Ch.; Rasiński, M.; Kreter, A.; Tan, Xiao–Yue; Schmitz, J.; Coenen, J. W.; Mao, Y.; González‐Julián, Jesús; Bram, Martin

doi:10.1088/1402-4896/aa81f5

Cited by 38 publications

(36 citation statements)

References 19 publications

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“…Furthermore, samples are cooled at a rate of 300 °C min −1 . The microstructure obtained after sintering is characterised by submicrometer-sized grains of W-Cr solid solution with finely dispersed yttria particles with a size of < 150 nm [5]. More details on the sample production and resulting microstructure can be found in Ref.…”

Section: Plasma Exposurementioning

confidence: 99%

“…More details on the sample production and resulting microstructure can be found in Ref. [5]. For the sintered WCrY samples, WCrY1-4 relative densities of 98.6%, 91.2%, 93.2%, and 98.4% of the theoretical 100% density, assuming a composition of W-11.4 wt.%Cr-0.6 wt.%Y, are obtained.…”

Section: Plasma Exposurementioning

confidence: 99%

“…Y facilitates the Cr transport towards the alloy's surface during oxidation; it adds to the stability of the oxide scale and supports the formation of a continuously growing, well-adhering and dense Cr 2 O 3 layer [4]. It was shown that WCrY-systems can suppress the oxidation rate significantly compared to that of pure W [5,6].…”

Section: Introductionmentioning

confidence: 99%

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Argon-seeded plasma exposure and oxidation performance of tungsten-chromium-yttrium smart alloys

et al. 2019

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Tungsten-chromium-yttrium (WCrY) smart alloys are foreseen as the first wall material for future fusion devices such as Demonstration Power Plant (DEMO). While suppressing W oxidation during accidental conditions, they should behave like pure W during plasma operation due to preferential sputtering of the lighter alloying elements Cr, Y, and W enrichment of the surface. In this paper, the erosion performance of WCrY and W samples simultaneously exposed to deuterium (D) plasma with the addition of 1% of the projectile ions being argon (Ar) ions at an ion energy of 120 eV is compared. With reference to the previous experiments at 120 eV in pure D plasma, the erosion for both WCrY and W is enhanced by a factor of ~ 7. Adding Ar to the D plasma suppresses significant W enrichment previously found for pure D plasma. To investigate the impact of the plasma exposure onto the oxidation performance, plasma-exposed and non-exposed reference samples were oxidised in a dry atmosphere. Results show, on the one hand, that the oxidation suppression of WCrY in comparison to pure W is preserved during the plasma performance. On the other hand, it becomes evident that edge effects imposed by the geometry of the samples used in plasma experiments play a significant role for the oxidation behaviour.

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Section: Plasma Exposurementioning

confidence: 99%

Section: Plasma Exposurementioning

confidence: 99%

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Argon-seeded plasma exposure and oxidation performance of tungsten-chromium-yttrium smart alloys

et al. 2019

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“…WCrY alloys were recently developed and tested in laboratory experiments (oxidation resistance) and in a plasma environment [5]. Plasma exposure of WCrY samples in the linear plasma device PSI-2 and subsequent analysis by secondary ion mass spectrometry confirm surface enrichment of W caused by preferential sputtering of Cr [6].…”

Section: Introductionmentioning

confidence: 99%

Segregation and preferential sputtering of Cr in WCrY smart alloy

Koslowski

Schmitz

Linsmeier

2020

Nuclear Materials and Energy

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The temperature driven segregation of Cr to the surface of the tungsten-based WCrY alloy is analysed with low energy ion scattering of He + ions with an energy of 1 keV in the temperature range from room temperature to 1000 K. Due to the high surface sensitivity, these measurements probe only the composition of the outermost monolayer. The surface concentration of Cr increases slightly when the temperature of the sample is increased up to 700 K and exhibits a much stronger increase when the sample temperature is further raised. The segregation enthalpy for Cr is obtained from the Langmuir-McLean relation and amounts to 0.7 eV. The surface concentration of Y shows a similar behaviour to the Cr concentration. The temperature thresholds between slow and accelerated surface density increases for Cr and Y are nearly the same. At a temperature of 1000 K the low energy ion scattering detects almost no W on the surface. The modified surface composition due to the segregated species, i.e. the mixed Cr/Y layer, stays stable during cool-down of the sample. Preferential sputtering is investigated using ion bombardment of 250 eV D atoms, resulting in an increase of the W surface density at room temperature. This effect is counteracted at elevated temperatures where segregation replenishes the lighter elements on the surface and prevents the formation of an all-W surface layer. The flux of segregating Cr atoms towards the surface is evaluated from the equilibrium between sputter erosion and segregation.

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“…Multiple attempts have been undertaken to promote oxidation resistance of tungsten-based materials by proposing several ternary (W-Cr-Y 'smart alloys' [16,17,18,19]) and quaternary (W-Mo-Cr-Pd [20,21,22]) tungsten alloys. Although some results look promising, the new material is still unlikely to withstand an extended LOCA event, which could last for up to three months.…”

Section: Introductionmentioning

confidence: 99%

Probing the correlation between phase evolution and growth kinetics in the oxide layers of tungsten using Raman spectroscopy and EBSD

Fulton

Lunev

2020

Corrosion Science

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Tungsten, a plasma-facing material for future fusion reactors, may be exposed to air during abnormal operation or accidents. Only limited information is available on the evolution of related oxide phases. This work addresses the effect of substrate orientation on structural variations of tungsten oxides. Annealing experiments in an argon-oxygen atmosphere have been conducted at T = 400°C under varying oxygen partial pressure and oxidation time. A combination of EBSD, Raman spectroscopy and confocal microscopy shows preferential oxidation initially on {1 1 1} base material planes. The oxide scale changes its phase composition dynamically, influencing the kinetics of its growth.

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New oxidation-resistant tungsten alloys for use in the nuclear fusion reactors

Cited by 38 publications

References 19 publications

Argon-seeded plasma exposure and oxidation performance of tungsten-chromium-yttrium smart alloys

Argon-seeded plasma exposure and oxidation performance of tungsten-chromium-yttrium smart alloys

Segregation and preferential sputtering of Cr in WCrY smart alloy

Probing the correlation between phase evolution and growth kinetics in the oxide layers of tungsten using Raman spectroscopy and EBSD

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