Tungsten as Structural Material

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Tungsten as Structural Material

• for Power Plant High Heat Flux Components

Contents - Overview- Materials
Microstructure - Strength - Thermal
Conductivity - Toughness - Conclusions and
Outlook
Michael Rieth Andreas Hoffmann
Thanks for contributions and discussions to S.
Baumgärtner, C. Bichler, B. Dafferner, C.
Grubich, S. Heger, U. Jäntsch, M. Klimenkov, W.
Krauss, P. Lukits, E. Materna-Morris, A.
Möslang, P. Norajitra, J. Reiser, M. Rohde, W.
Schulmeyer, R. Ziegler, H. Zimmermann
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Overview, DEMO Divertor Design
ELMs, high energetic particles, etc.
10 MW/m²
1700C
Tile (W)
1200C (Brazed Joint)
Thimble (W-Material)
Conic Sleeve (ODS Steel)
700C(Brazed Joint)
ODS Steel
Cartridge(W, Steel)
? P. Norajitra, this workshop
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Materials
Pure Tungsten
Grain Stabilized Tungsten
Tungsten Compounds
Tungsten Alloys

• W-Cu (Elmet)
• W-Ni-Fe (Densimet)
• W-Ag

• W-Mo
• W-Ta
• W-V

Potassium Doping
Oxide Particles

• La2O3 (e.g. WL10)
• ThO2
• ZrO2
• CeO2

e.g. WVM ? Bulb Wire
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Material Production Routes
Melting Forming
Sintering Forming
Powder-Metallurgy
Mass Production Density -/ Specific,
aniso- tropic micro- structure

• Real Alloying
• Expensive (? EB, Arc, Vacuum, )

Mechanical Alloying HIP
Injection Molding Sintering/HIP

• Mass Production
• Nearly Finished Products
• Homogenous Microstructure
• Porosity
• Severe Brittleness

• Fine Particles
• Homogenous Microstructure
• Small Quantities
• Porosity
• Brittleness

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Important Design Criterions
Thermal Conductivity
100 W/mK _at_ 1200 C
Creep Strength
55 MPa, 20 kh _at_ 1200 C
DBTT (EU Mini Charpy)
300 C, un-irradiated
Recrystallization Temperature
1300 C, for 20 kh
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Present Knowledge Creep
\l(1) WL10 plate (4 mm)
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Present Knowledge Creep
commercial 8 mm WL10 rod (weld electrode)
commercial 8 mm W rod (weld electrode)
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Present Knowledge Recrystallization
Microstructure in the condition as delivered (by
TEM)
WL10 Rod, Ø7 mm
W Rod, Ø7 mm
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Present Knowledge Recrystallization
Microstructure perpendicular to rod axis (by
optical microscope)
W Rod, Ø10 mm, 1300 C/343 hours
W Rod, Ø10 mm, as delivered
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Present Knowledge Recrystallization
Microstructure parallel to rod axis (by optical
microscope)
WL10 Rod, Ø10 mm, 1300 C/1966 hours
WL10 Rod, Ø10 mm, as delivered
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Present Knowledge Recrystallization
Observed recrystallization compared to existing
results (Ref. Plansee)
Design Limit
???
W 1 La2O3 ???
20000 h
1300
start of recry- stallization
not recrystallized
1100
1 h
200 h
2 h
8 h
W
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Present Knowledge Th. Conductivity
parallel to rod axis
Design Limit
perpendicular to plate
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Materials, Rolling Texture
6 RODS
4 PLATES
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Microstructure
WL10 Rod, Ø7 mm
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Microstructure
W-1Re-1La2O3 Rod, Ø10 mm
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Present Knowledge DBTT
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Present Knowledge DBTT
7 mm WL10 rod
commercial 8 mm W rod (weld electrode)
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High Temperature Charpy Tests
vacuum 10-6 Bar / 1150C
drop weight
tup
support
specimen
drop weight design, vacuum vessel
opened furnace view on support
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Results, Rod Materials
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Fracture W WL10, 7 mm rods
W 7 mm rod, EDM WL10 7 mm rod, EDM
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Surface Fabrication
W Rod, Diamond Saw
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Delamination, Simple Analogy
a
b
c
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Results, Surface Fabrication
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Discussion
Shift due to surface cracks ? fabrication issue
Delamination crack initiation ? fabrication issue
Shift due to load ? specimen geometry (stress
concentration)
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Results, Plate Materials
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Fracture W WL10, plates
WL10
W
26 M. Rieth Institute for Materials
Research I 17.10.2007
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Discussion

• GB weakening
• type, size, distrib. of oxides
• grain shape, orientation, etc.

Base Material Mo - W ? DBTT characteristic
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Present Knowledge DBTT
7 mm WL10 rod
7 mm W rod
commercial 8 mm W rod (weld electrode)
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Conclusions