Evolution of vacancy defects in heavy ion irradiated tungsten exposed to helium plasma

Dislocation loop and gas bubble evolution in tungsten were in-situ investigated under 30 keV H 2 + and He + dual-beam irradiation at 973 K and 1173 K. The average size and number density of dislocation loops and gas bubbles were obtained as a function of irradiation dose. The quantitative calculation and analysis of the migration distance of 1/2 ⟨111⟩ loops at low irradiation dose indicated that the main mechanism of the formation of ⟨100⟩ loops should be attributed to the high-density helium cluster inducement mechanism, instead of the 1/2 ⟨111⟩ loop reaction mechanism. H 2 + and He + dual-beam irradiation induced the formation of ⟨100⟩ loops and 1/2 ⟨111⟩ loops, while increasing the irradiation temperature would increase ⟨100⟩ loop percentage. The percentage of ⟨100⟩ loops was approximately 18.6% at 973 K and increased to 22.9% at 1173 K. The loop reaction between two 1/2 ⟨111⟩ loops to form a large-sized 1/2 ⟨111⟩ loop was in-situ observed, which induced not only the decrease of the number of 1/2 ⟨111⟩ loops but also the significant increase of their sizes. The ⟨100⟩ loops impeded the movement of dislocation line and tended to escape from it instead of being absorbed. With the increase of irradiation dose, the yield strength increment ( Δ loop ) caused by the change of loop size and density increased first and then decreased slightly, while the yield strength increment ( Δ bubble ) caused by the change of bubble size and density always increased. Meanwhile, within the current irradiation dose range, Δ loop was much larger than Δ bubble .

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“…The irradiation behavior of tungsten has been widely researched in recent years [9][10][11]. A series of important results are obtained.…”

Section: Introductionmentioning

confidence: 99%

In-situ transmission electron microscopy observation of the evolution of dislocation loops and gas bubbles in tungsten during H2+ and He+ dual-beam irradiation

Ding

Liu

et al. 2021

Tungsten

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“…Excessive H atoms and self‐interstitial W atoms generated via loop punching diffuse into the bulk layer and remain in defects such as dislocations and vacancies, which can reduce the capture rate of positrons and increase the annihilation probability of positrons with high‐momentum electrons, leading to a reduction in the S‐parameter of the bulk zone. [ 36,42 ]…”

Section: Resultsmentioning

confidence: 99%

“…In the bulk layer, the dislocation loops generated by He loop punching in pure W, which are pinned by K bubbles in the WK alloy, diffuse to the matrix and react with intrinsic vacancies in the samples, decreasing the concentration and volume of vacancy‐type defects, and leading to a reduction in the S‐parameter of PW‐800. [ 11,31,42 ]…”

Section: Resultsmentioning

confidence: 99%

Vacancy‐Type Defects in H+6%He Neutral Beam Irradiated WK Alloy Probed by Slow Positron Beam

Liu

Pei-Yuan

et al. 2021

Physica Status Solidi (a)

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H+6%He mixed neutral beam with a power density of 8 MV m−2 and fluence of 1025 m−2 is produced to induce irradiation damage at surface temperatures of 400, 800, and 1300 °C in WK alloy, and at 400 and 800 °C in pure W samples. Doppler‐broadening positron annihilation spectroscopy (DB‐PAS) and X‐ray diffraction (XRD) are used to probe the evolution of vacancy‐type defects in the samples after irradiation. The results show that for the WK alloy, the S‐parameters for the 400, 800, and 1300 °C samples increase sequentially because of the increase in vacancy‐type defect concentrations or volumes. The WK sample at 1300 °C exhibits a wider defect damage layer and more complicated vacancy‐type defects than those in the WK samples at 400 and 800 °C. For pure W, the S‐parameter of the 800 °C samples is larger than that of the 400 °C samples, which is attributed to the aggregation and growth of vacancy‐type defects. Based on a comparison of the WK and pure W samples, the pinning effect of K bubbles in the WK samples has an influence on the transportation of H/He atoms and the migration and aggregation of vacancy‐type defects.

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“…The cross-sectional transmission electron microscope (JEM-2100F, JEOL) images were taken for both un-irradiated and irradiated samples (at 200 keV). The 50 ~70 nm thick TEM samples were prepared by using a focused ion beam milling (3D FEG, Quanta) [35][36][37] with 30 kV Ga-ions (7 nA ~50pA). Before the milling process, a protective layer of Pt was deposited to prevent ion damages.…”

Section: Film Characterizationsmentioning

confidence: 99%

Combinatorial Discovery of Irradiation Damage Tolerant Nano-structured W-based alloys

Jo¹,

Park²,

You³

et al. 2022

Preprint

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One of the challenges in fusion reactors is the discovery of plasma facing materials capable of withstanding extreme conditions, such as radiation damage and high heat flux. Development of fusion materials can be a daunting task since vast combinations of microstructures and compositions need to be explored, each of which requires trial-and-error based irradiation experiments and materials characterizations. Here, we utilize combinatorial experiments that allow rapid and systematic characterizations of composition-microstructure dependent irradiation damage behaviors of nanostructured tungsten alloys. The combinatorial materials library of W-Re-Ta alloys was synthesized, followed by the high-throughput experiments for probing irradiation damages to the mechanical, thermal, and structural properties of the alloys. This highly efficient technique allows rapid identification of composition ranges with excellent damage tolerance. We find that the distribution of implanted He clusters can be significantly altered by the addition of Ta and Re, which play a critical role in determining property changes upon irradiation.

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Evolution of vacancy defects in heavy ion irradiated tungsten exposed to helium plasma

Cited by 24 publications

References 57 publications

In-situ transmission electron microscopy observation of the evolution of dislocation loops and gas bubbles in tungsten during H2+ and He+ dual-beam irradiation

In-situ transmission electron microscopy observation of the evolution of dislocation loops and gas bubbles in tungsten during H2+ and He+ dual-beam irradiation

Vacancy‐Type Defects in H+6%He Neutral Beam Irradiated WK Alloy Probed by Slow Positron Beam

Combinatorial Discovery of Irradiation Damage Tolerant Nano-structured W-based alloys

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