Coupled motion of grain boundaries in bcc tungsten as a possible radiation-damage healing mechanism under fusion reactor conditions

Borovikov, V. A.; Tang, Xian-Zhu; Pérez, Danny; Bai, Xian-Ming; Uberuaga, Blas P.; Voter, Arthur F.

doi:10.1088/0029-5515/53/6/063001

Cited by 36 publications

(46 citation statements)

References 39 publications

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“…Further annealing leads to rearrangement of the disordered Fe atoms within the GB, and at about 10 ps GB reconstruction occurs, where a new atomic layer forms above the original GB plane, which is clearly shown in the final snapshot. We also observed that some single [32]. This will be a topic for future investigations.…”

Section: σ3 Gb With 10% Hesupporting

confidence: 61%

Atomistic simulations of helium clustering and grain boundary reconstruction in alpha-iron

et al. 2015

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The accumulation and clustering of He atoms at 3 <110> {112} and 73b<110>{661} grain boundaries (GBs) in bcc Fe, as well as their effects on GB reconstruction, have been investigated using atomic-level computer simulations. The accumulation of He atoms and the evolution of the GB structure all depend on local He concentration, temperature and the original GB structure. At a local He concentration of 1%, small He clusters are formed in the 3 GB, accompanied by the emission of single self-interstitial Fe atoms (SIAs). At a He concentration of 5%, a large number of SIAs are emitted from He clusters in the 3 GB and collect at the periphery of these clusters. The SIAs eventually form <100> dislocation loops between two He clusters. It is likely that impurities may promote the formation of <100> loops and enhance their stabilities in -Fe. At a He concentration of 10%, the large number of emitted SIAs are able to rearrange themselves, forming a new GB plane within the 3 GB, which results in self-healing of the GB and leads to GB migration. In contrast to the 3 GB, He clusters are mainly formed along the GB dislocation lines in the 73b, and the emitted SIAs are accumulate at the cores of the GB dislocations, leading to the climb of the dislocations within the GB plane. As compared to bulk Fe, a higher number density of clusters form at GBs, but the average cluster size is smaller. The product of cluster density and average cluster size is roughly constant at a given He level, is about the same in bulk and GB regions, and varies linearly with the He concentration.

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Section: σ3 Gb With 10% Hesupporting

confidence: 61%

Atomistic simulations of helium clustering and grain boundary reconstruction in alpha-iron

et al. 2015

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“…For example, Tschopp, Solanki and coworkers have performed extensive atomistic simulations to investigate the effects of GB character on the formation energetics of point defects, such as vacancy922232430, self-interstitial9, hydrogen2526, helium2627, carbon2628 and various other impurities2326. Aiming to mitigate radiation damage, Uberuaga, Demkowicz and coworkers have conducted massive multiscale simulations193132333435363738 to understand the effects of interface structure on point defect segregation, defect mobility, defect recombination and GB sink efficiency. Jiang et al 29.…”

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confidence: 99%

Energetics of vacancy segregation to [100] symmetric tilt grain boundaries in bcc tungsten

Chen

Niu

Zhang

et al. 2016

Sci Rep

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The harsh irradiation environment poses serious threat to the structural integrity of leading candidate for plasma-facing materials, tungsten (W), in future nuclear fusion reactors. It is thus essential to understand the radiation-induced segregation of native defects and impurities to defect sinks, such as grain boundaries (GBs), by quantifying the segregation energetics. In this work, molecular statics simulations of a range of equilibrium and metastable [100] symmetric tilt GBs are carried out to explore the energetics of vacancy segregation. We show that the low-angle GBs have larger absorption length scales over their high-angle counterparts. Vacancy sites that are energetically unfavorable for segregation are found in all GBs. The magnitudes of minimum segregation energies for the equilibrium GBs vary from −2.61 eV to −0.76 eV depending on the GB character, while those for the metastable GB states tend to be much lower. The significance of vacancy delocalization in decreasing the vacancy segregation energies and facilitating GB migration has been discussed. Metrics such as GB energy and local stress are used to interpret the simulation results, and correlations between them have been established. This study contributes to the possible application of polycrystalline W under irradiation in advanced nuclear fusion reactors.

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“…However, an alternative approach may be considered to eliminate the vacancies accumulated under irradiation. Borovikov et al [8] suggested that the SIAs filled GB can migrate in tungsten (W) under the fusion reactor conditions.…”

Section: Introductionmentioning

confidence: 99%

“…GB can migrate with the translation of grains if the shear stress is applied on the metallic materials and such GB migration may be defined as the coupled motion [8][9][10]. The common GB migration without stress is dominated by the diffusion of vacancies [11], and the coupled motion of GB is dominated by the collective movement of atoms [12].…”

Section: Introductionmentioning

confidence: 99%

“…The coupled motion has a lower migration barrier and higher migration speed compared with the common GB migration. Moreover, the SIAs can reduce the friction of the GB migration for some specific type of GB [8]. Under the fusion conditions, the normal heat load is 5-10 MW/m 2 , while the transient heat load can reach as high as several hundred MW/m 2 and even GW/m 2 with edged local modes (ELMs) and vertical displacement events (VDEs) [13].…”

Section: Introductionmentioning

confidence: 99%

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Effect of hydrogen on grain boundary migration in tungsten

Shu

Liu

et al. 2015

Sci. China Phys. Mech. Astron.

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Motivated by a grain boundary (GB) healing mechanism that GB turns into a mobile sink through migration to eliminate the vacancies in a bulk, we have further investigated the influence of the retained hydrogen (H) on the GB migration in tungsten using a molecular dynamics simulation. We show that H hinders the GB migration at different H concentrations and temperatures, and such friction of GB migration due to the presence of H increases with the H concentration and decreases with temperature. We demonstrate that H follows the GB-migration as the temperature is higher than 300 K. Most importantly, the presence of H induces a disordering of GB, which affects the GB migration significantly. tungsten grain boundary, hydrogen, migration, molecular dynamics, disordering PACS number(s): 28.52.Fa, 61.72.Mm, 61.82.Bg, 31.15.Qg Citation: Yu Y, Shu X L, Liu Y N, et al. Effect of hydrogen on grain boundary migration in tungsten.

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Coupled motion of grain boundaries in bcc tungsten as a possible radiation-damage healing mechanism under fusion reactor conditions

Cited by 36 publications

References 39 publications

Atomistic simulations of helium clustering and grain boundary reconstruction in alpha-iron

Atomistic simulations of helium clustering and grain boundary reconstruction in alpha-iron

Energetics of vacancy segregation to [100] symmetric tilt grain boundaries in bcc tungsten

Effect of hydrogen on grain boundary migration in tungsten

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