Recrystallization and grain growth induced by ELMs-like transient heat loads in deformed tungsten samples

Suslova, Anastassiya; El-Atwani, Osman; Sagapuram, Dinakar; Harilal, S. S.; Hassanein, A.

doi:10.1038/srep06845

Cited by 76 publications

(31 citation statements)

References 43 publications

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“…Electron beams [12][13][14][15], pulsed lasers [16][17][18][19][20] and plasma generators [16,21,22] are usually exploited at the laboratory scale as dedicated facilities for the high heat flux testing of W PFCs, both in the bulk or in the coating form, under ITERrelevant transient conditions. These techniques usually rely on the use of temporal rectangular pulsed beams with a comparable pulse duration of plasma transient events (i.e.…”

Section: Introductionmentioning

confidence: 99%

Nanosecond laser pulses for mimicking thermal effects on nanostructured tungsten-based materials

et al. 2018

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In this work, we exploit nanosecond laser irradiation as a compact solution for investigating the thermomechanical behavior of tungsten materials under extreme thermal loads at the laboratory scale. Heat flux factor thresholds for various thermal effects, such as melting, cracking and recrystallization, are determined under both single and multishot experiments. The use of nanosecond lasers for mimicking thermal effects induced on W by fusionrelevant thermal loads is thus validated by direct comparison of the thresholds obtained in this work and the ones reported in the literature for electron beams and millisecond laser irradiation. Numerical simulations of temperature and thermal stress performed on a 2D thermomechanical code are used to predict the heat flux factor thresholds of the different thermal effects. We also investigate the thermal effect thresholds of various nanostructured W coatings. These coatings are produced by pulsed laser deposition, mimicking W coatings in tokamaks and W redeposited layers. All the coatings show lower damage thresholds with respect to bulk W. In general, thresholds decrease as the porosity degree of the materials increases. We thus propose a model to predict these thresholds for coatings with various morphologies, simply based on their porosity degree, which can be directly estimated by measuring the variation of the coating mass density with respect to that of the bulk.

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Section: Introductionmentioning

confidence: 99%

Nanosecond laser pulses for mimicking thermal effects on nanostructured tungsten-based materials

et al. 2018

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“…Recrystallization texture of W has been characterized via Electron Back-Scattered Diffraction (EBSD) technique [24][25][26][27][28]. In [24], γand α fiber rolling textures were replaced by random texture with a slight cube component in recrystallized W due to the oriented nucleation of cube nuclei.…”

Section: Introductionmentioning

confidence: 99%

“…In [27], the rolled W foil showed a pronounced {100}〈011〉 texture while the annealed one displayed a texture varying between {100}〈011〉 and {112}〈011〉. In [28], surface recrystallization was achieved on the severely deformed W and cold rolled W via transient high heat flux of laser beam. The severely deformed W exhibited random orientation while the cold rolled one showed the {hkl}〈001〉 orientation.…”

Section: Introductionmentioning

confidence: 99%

Texture evolution of tungsten materials during recrystallization

Zhang¹,

Zheng²,

Huang³

et al. 2020

Mater. Res. Express

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Some functional and structural performance of tungsten (W) are related to its texture characteristics. Usually, W serves in high temperature and may undergo recrystallization. Thus it's necessary to evaluate the recrystallization texture of W. In our previous studies, pure W (PW) and W-1.0wt%La 2 O 3 (WL10) were deformed via unidirectional rolling (UNR), cross rolling (CRR) and clock rolling (CLR) with 80% reduction. In the present paper, PW-UNR, PW-CRR, PW-CLR and WL10-UNR were subjected to annealing at 2073 K for 2 h to achieve recrystallization and figure out the evolution mechanism of recrystallization texture in W materials. Besides, the effect of La 2 O 3 on recrystallization texture of W was discussed. The results indicated that the fiber textures in rolling state were transformed into isolated textures after recrystallization. {001}〈uvw〉 isolated texture formed in the recrystallized W may be mainly resulted from the texture inheritance. {113}〈361〉 isolated texture formed in the recrystallized WL10-UNR may be attributed to the orientated growth of {113}〈361〉 grains with high grain boundary mobility facilitated by La 2 O 3 . Generally, isolated textures near θ-fiber were strengthened while γ-fiber was weakened for W during recrystallization, which is an effective method to achieve W with more {001} and less {111} textures.

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“…However, PFMs are still subjected to the high-energy transient heat load because of the instability of plasma, such as vertical displacement events (VDEs, ~ 60 MJ m −2 , ~ 300 ms) and edge-localized modes (ELMs, ~ 1 MJ m −2 , < 0.5 ms) [12,13]. Such a high-energy density can lead to recrystallization (for deformed W materials), surface melting, ablation, cracking, and other serious irreversible damages for PFMs [14], resulting in reducing its basic physical properties and shortening its service life [15,16]. The particle irradiation from the plasma also causes some damages for PFMs.…”

Section: Introductionmentioning

confidence: 99%

Microstructure evolutions of the W–TiC composite conducted by dual-effects from thermal shock and He-ion irradiation

et al. 2019

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Considering that tungsten (W) materials served as the plasma-facing material in the fusion reactor would be exposed to edgelocalized modes (ELMs)-like thermal shock loading accompanied with He-ion irradiation, the W-TiC composite produced with a wet-chemical method was conducted by the dual effects from the laser beam thermal shock first and He-ion irradiation later in this work. The microstructure changes of the W-TiC composite before and after two tests were characterized by scanning electron microscopy or transmission electron microscopy. After the laser beam thermal shock test, there was an obvious interface on the exposed surface of the W-TiC composite. Several main cracks and melting areas could be found nearby the interface and center, respectively. Furthermore, a mixture of tungsten oxide and TiC was easy to aggregate and form into circle areas surrounding the melting area. The thermal shock tested that W-TiC composite was then subjected to the He-ion irradiation. The typical features of fuzz structures could be detected on the surface of the W-TiC composite apart from the center of the melting area. Notably, several nano-sized He bubbles deeply distributed at grain boundaries in the melting area, owing to the grain boundary functioning as the free path for He diffusion.

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Recrystallization and grain growth induced by ELMs-like transient heat loads in deformed tungsten samples

Cited by 76 publications

References 43 publications

Nanosecond laser pulses for mimicking thermal effects on nanostructured tungsten-based materials

Nanosecond laser pulses for mimicking thermal effects on nanostructured tungsten-based materials

Texture evolution of tungsten materials during recrystallization

Microstructure evolutions of the W–TiC composite conducted by dual-effects from thermal shock and He-ion irradiation

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