Impact of plastic deformation on plasma induced damage and deuterium retention in tungsten

MRS Advances ◽  
2017 ◽  
Vol 2 (55) ◽  
pp. 3347-3352 ◽  
Author(s):  
A. Bakaeva ◽  
D. Terentyev ◽  
A. Dubinko
Keyword(s):  
Surface Layer ◽  
Dislocation Line ◽  
Experimental Studies ◽  
Thermal Desorption Spectroscopy ◽  
Bubble Nucleation ◽  
Dislocation Network ◽  
High Flux ◽  
Plasma Exposure ◽  
Deuterium Retention ◽  
Core Migration

ABSTRACTRecent theoretical and subsequent experimental studies suggest that the uptake and release of deuterium (D) in tungsten (W) under high flux ITER-relevant plasma exposure is controlled by dislocation microstructure. Thanks to numerical calculations, a comprehensive mechanism for the nucleation and growth of D bubbles on dislocation network was proposed. The process of bubble nucleation can be described as D atom trapping at a dislocation line, its in-core migration, the coalescence of several D atoms into a multiple cluster eventually transforming into a nano-bubble. This view implies that the initial microstructure might be crucial for D uptake and degradation of the sub-surface layer under prolonged plasma exposure. In this work, we apply several experimental techniques to investigate the microstructure and mechanical properties of surface and sub-surface layer of W in recrystallized and plastically-deformed condition exposed to the high flux plasma. We use transmission and scanning electron microscopy, thermal desorption spectroscopy as well as nano-indentation measurements.

Surface Modification and Deuterium Retention in Tungsten and Molybdenum Exposed to Low-Energy, High Flux Deuterium Plasmas

2008 ◽  
Vol 59 ◽  
pp. 42-45
Author(s):  
Vladimir K. Alimov ◽  
Wataru M. Shu ◽  
J. Roth ◽  
D.A. Komarov ◽  
Stefan Lindig ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Surface Layer ◽  
Thermal Desorption Spectroscopy ◽  
Low Energy ◽  
High Flux ◽  
Plasma Exposure ◽  
Near Surface ◽  
Exposure Temperature ◽  
Deuterium Retention ◽  
Scanning Electron

Deuterium retention in single crystal and polycrystalline tungsten and molybdenum exposed to low-energy (38200 eV/D), high ion flux (10211022 D/m2s) deuterium plasmas at various temperatures were examined with the D(3He,p)4He nuclear reaction at a 3He energy varied from 0.69 to 4.0 MeV, and with thermal desorption spectroscopy. The surface morphology was examined by scanning electron microscope. Blisters formed on the Mo surfaces under plasma exposure are significantly larger in size than those for W. The D retention in the W and Mo samples increases with the exposure temperature, reaching its maximum at about 500 and 530 K (for ion fluxes of 1021 and 1022 D/m2/s), respectively, and then decreases as the temperature grows further. For polycrystalline W and Mo exposed at temperatures above 400 K, the D retention in the bulk (far beyond the ion implanted zone) is dominant. Plastic deformation caused by deuterium super-saturation within the near-surface layer is suggested as a mechanism for blister formation and creation of defects responsible for deuterium trapping at depths up to several micrometers.

scholarly journals Fluence Dependence of Surface Morphology and Deuterium Retention in W Bulks and Nanocrystalline W Films Exposed to Deuterium Plasma

2021 ◽  
Vol 11 (4) ◽  
pp. 1619
Author(s):  
Jing Yan ◽  
Xia Li ◽  
Kaigui Zhu
Keyword(s):  
Surface Morphology ◽  
Thermal Desorption Spectroscopy ◽  
Low Energy ◽  
High Flux ◽  
Deuterium Plasma ◽  
Vacancy Clusters ◽  
Plasma Irradiation ◽  
Deuterium Retention ◽  
Fluence Dependence ◽  
Scanning Electron

The surface morphology of pure W bulks and nanocrystalline tungsten films was investigated after exposure to a low-energy (100 eV/D), high-flux (1.8 × 1021 D·m−2s−1) deuterium plasma. Nanocrystalline tungsten films of 6 μm thickness were deposited on tungsten bulks and exposed to deuterium plasma at various fluences ranging from 1.30 × 1025 to 5.18 × 1025 D·m−2. Changes in surface morphology from before to after irradiation were studied with scanning electron microscopy (SEM). The W bulk exposed to low-fluence plasma (1.30 × 1025 D·m−2) shows blisters. The blisters on the W bulk irradiated to higher-fluence plasma are much larger (~2 µm). The blisters on the surface of W films are smaller in size and lower in density than those of the W bulks. In addition, the modifications exhibit the appearance of cracks below the surface after deuterium plasma irradiation. It is suggested that the blisters are caused by the diffusion and aggregation of the deuterium-vacancy clusters. The deuterium retention of the W bulks and nanocrystalline tungsten films was studied using thermal desorption spectroscopy (TDS). The retention of deuterium in W bulks and W films increases with increasing deuterium plasma fluence when irradiated at 500 K.

Trapping and release of helium and deuterium in recrystallized and heavily deformed tungsten after plasma exposure

2020 ◽  
Vol 05 (01) ◽  
pp. 2050002
Author(s):  
A. Bakaeva ◽  
D. Terentyev ◽  
G. De Temmerman ◽  
L. Cheng ◽  
G.-H. Lu
Keyword(s):  
Thermal Desorption Spectroscopy ◽  
High Flux ◽  
Plasma Exposure ◽  
Material Microstructure ◽  
Mixed Beam ◽  
Fusion Applications ◽  
Tungsten Surface ◽  
Tremendous Importance ◽  
The Impact ◽  
Release Processes

Interaction of tungsten surface with plasma beam has tremendous importance for development of materials for fusion applications. Trapping and release of Helium (He) and Deuterium (D) in tungsten exposed to high flux plasma with varying He and D content are studied here. Recrystallized and plastically deformed tungsten samples were used to clarify the impact of the material microstructure on trapping and release of plasma components. Thermal desorption spectroscopy measurements were performed to reveal the release stages and quantify the integral desorption of both types of molecules. Comparison of reference and plastically deformed samples was used to clarify the impact of plastic deformation (expressed in the high dislocation density and dislocation networks) on the trapping and release processes. It has been demonstrated that in the mixed beam exposures, the integral He release weakly depends on the He/D ratio, but suddenly grows as the fraction of He/D increases from 80/20 to 100/0. The integral release of D is remarkably enhanced by He seeding in both reference and plastically deformed samples. It is concluded that under the mixed beam exposure conditions, the D release is primary controlled by the He seeding and not by the deformation-induced microstructure.

scholarly journals Surface morphology and deuterium retention of tungsten after low- and high-flux deuterium plasma exposure

2014 ◽  
Vol 54 (8) ◽  
pp. 083014 ◽  
Author(s):  
M.H.J. 't Hoen ◽  
M. Balden ◽  
A. Manhard ◽  
M. Mayer ◽  
S. Elgeti ◽  
...  
Keyword(s):  
Surface Morphology ◽  
High Flux ◽  
Deuterium Plasma ◽  
Plasma Exposure ◽  
Deuterium Retention

scholarly journals Comparative study of surface modification and D retention between beryllium and beryllides under high flux plasma exposure

2021 ◽  
pp. 101014
Author(s):  
M. Miyamoto ◽  
Y. Sugimoto ◽  
D. Nishijima ◽  
M.J. Baldwin ◽  
R.P. Doerner ◽  
...  
Keyword(s):  
Surface Modification ◽  
Comparative Study ◽  
High Flux ◽  
Plasma Exposure

scholarly journals The high-flux effect on deuterium retention in TiC and TaC doped tungsten at high temperatures

2017 ◽  
Vol 494 ◽  
pp. 211-218 ◽  
Author(s):  
Mikhail Zibrov ◽  
Kirill Bystrov ◽  
Matej Mayer ◽  
Thomas W. Morgan ◽  
Hiroaki Kurishita
Keyword(s):  
High Temperatures ◽  
High Flux ◽  
Deuterium Retention

scholarly journals INCREASING THE EFFICIENCY OF SURFACE STRENGTHENING OF METAL PRODUCTS BY COMBINED THERMODEFORMATION PROCESSING

2020 ◽  
pp. 103-110
Author(s):  
Oleksandr Danyleiko ◽  
Vitaliy Dzhemelinskyi ◽  
Dmytro Lesyk ◽  
Artemii Bernatskyi
Keyword(s):  
Surface Layer ◽  
Laser Beam ◽  
Surface Hardening ◽  
Thermal Deformation ◽  
Experimental Studies ◽  
Numerical Control ◽  
Surface Plastic ◽  
Beam Diameter ◽  
Metal Products ◽  
Deformation Surface

The article discusses the prospects of using combined thermal deformation surface processing to improve the performance properties of metal products. There is a new method of thermal deformation surface hardening (shot peening (SP) followed by laser heat treatment (LHT)) for tools and crown housings operating under difficult conditions proposed. For carrying out experimental studies, flat samples of 30KhGSA steel and steel 45 were selected. Preliminary hardening and finishing with static or dynamic methods of surface plastic deformation were carried out on a modernized installation based on a DYNAMITE 2800 numerical control machine, and SP was implemented on industrial equipment. Laser surface hardening of the samples was carried out in single passes with a sample moving speed of 300...500 mm/min with a laser beam diameter of 7.3 mm and a laser power of 1 kW using the ROFIN-SINAR DY 044 technological unit. The optimal regimes of surface hardening are determined under the deformation action of a gas-dynamic flow with solid particles and thermal action by a laser beam to obtain maximum values ​​of hardening depth and hardness. In particular, with SP, the gas-feed stream feed pressure is 0.5 MPa, the processing time is 1 min, regardless of the type of material. The optimal laser beam power is 1 kW at a sample travel speed of 300 mm/min. There are the results of experimental studies of the change in the hardening depth as a function of time and pressure after SP, the speed of movement of the treated sample from carbon steel 45 and medium alloyed steel 30KhGSA after LHT and combined SP+LHT, and also the distribution of microhardness over the depth of the hardened layer presented. It is revealed that the combined SP+LHT of 30 KhGSA steel at optimal modes forms 1.5 times (1.3 mm) greater depth of the strengthened surface layer in comparison with LHT, while providing the surface layer hardness of ~5400 MPa.

Theoretical and experimental studies of the oil film in lubricated point contact

1966 ◽  
Vol 291 (1427) ◽  
pp. 520-536 ◽  
Keyword(s):  
Surface Layer ◽  
Film Thickness ◽  
Strong Evidence ◽  
Experimental Studies ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Experimental Results ◽  
Point Contacts ◽  
Previous Theory ◽  
Oil Film

A technique using Newton’s rings for mapping the oil film of lubricated point contacts is described. A theoretical value for the film thickness of such contacts in elastohydrodynamic lubrication is derived. The experimental results give the exit constriction predicted by previous theory but never shown in detail. The comparison of theoretical and experimental oil film thicknesses, which is satisfactorily accurate, gives strong evidence for a viscous surface layer some 1000Å thick. This film agrees with the known ‘lubricating power’ of the various oils tested.

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