of 26 slides

1
Program of the EFDA Materials Topical Group (FMTG)

• Sehila M. Gonzalez de Vicente
• Material Responsible Officer
• EFDA Close Support Unit - Garching

2
FUSION MATERIALS TOPICAL GROUP

• MAT-REMEV Radiation Effects Modelling and
  Experimental Validation
• Phase Stability and He dpa Accumulation Trigger
  in-service Properties of Materials in DEMO
  Magnetic Cluster Expansion a ??g phase
  transition points in Fe, and Rate Theory
  He-desorption from pre-implanted Fe-C alloys.
• MAT-ODSFS Nano-structured ODS Ferritic Steel
  Development
• - Improve the present generation of
  nano-structured ODS RAF steels
• - Start the industrial fabrication of the present
  generation of nano-structured ODS RAF steels-
  Develop an optimised generation of
  nano-structured and nano-grained ODS RAF steels-
  Investigate the stability of present and
  optimised generation of nano-structured ODS RAF
  steels under creep and irradiation

3
FUSION MATERIALS TOPICAL GROUP

• MAT-WWALLOYS Tungsten and Tungsten Alloys
  Development
• - Development of Structural Tungsten Materials
• - Optimization of Tungsten Armour Materials
• - Manufacturing Parts of Tungsten Materials
• Materials Science and Modeling
• The long-term objective of the EFDA fusion
  materials programme is to develop structural as
  well as armour materials in combination with the
  necessary production and fabrication technologies
  for future divertor concepts
• MAT-SiC/SiC SiCf/SiC Composite for Structural
  Application in Fusion Reactor
• - Processing techniques for manufacturing
  SiCf/SiC
• Increase in thermal conductivity

4
MAT-REMEVRadiation Effects Modelling and
Experimental Validation
5

• Phase Stability and He dpa Accumulation
• Trigger in-service Properties of Materials in
  DEMO
• Magnetic Cluster Expansion a ??g phase
  transition points in Fe.
• Rate Theory He-desorption from pre-implanted
  Fe-C alloys.

6
Magnetism Stabilises bcc Fe at low Temperature
At 0K the lowest Energy Ferro-Magnetic (FM) bcc
Fe
Magnetic Cluster Expansion (MCE) Fitted on DFT
data at 0K
Atomic Configuration Energy with Explicit
Magnetism Contribution
Allows Calculating Free Energy Phase Stability
at any Finite Temperature
7
Magnetic Cluster Dynamics
Monte Carlo Simulation of the Free
Energy Configuration Entropy Magnetic Excitation
Entropy Experimental Phonons entropy
Monte Carlo Simulation of the Free
Energy Configuration Entropy Magnetic Excitation
Entropy
Adding Phonons entropy based on experimental
data (Neutron Diffraction Elastic Constants
Not sufficient to Stabilise the fcc (g) at High
Temperature
For the First Time the high T g domain of iron
is predicted based on DFT and Atomistic
Modelling Experimental data
8
He-desorption from Fe-C Rate Theory Modelling
(i) DFT Energetics of He, Vacancies and Carbon
in a-Fe
He Binding Energy to Hen-1Vm
C Binding Energy to VCm-1
Hen-1Vm Heint ? HenVm
VCm-1 C ? VCm
He Binding Energy to Hen-1CVm
V He ? HeV Eb 2.3 eV
Carbon reduces the He-V binding energy
9
He-desorption from Fe-C Rate Theory Modelling
(ii) DFT based Rate Theory Modelling as function
of C content
Pure a-Fe
a-Fe with 50 appm Carbon

• C-V Binding Energies
• and
• He-V Binding Energy Reductions
• Favour He Desorption

a-Fe with 88 appm Carbon
Submitted Phys. Rev. B
10
MAT-ODSFSNano-structured ODS Ferritic Steel
Development
11
The 2008-2009 work programme of the European
research project on nano-structured ODS RAF
steels is being organized along four programmatic
lines

• Improve the present generation of
  nano-structured ODS RAF steels
• Start the industrial fabrication of the present
  generation of nano-structured ODS RAF steels
• Develop an optimised generation of
  nano-structured and nano-grained ODS RAF steels
• Investigate the stability of present and
  optimised generation of nano-structured ODS RAF
  steels under creep and irradiation

12
Improve the present generation of nano-structured
ODS RAF steels
MaterialsFe-(12-13-14)Cr-(1-2)W-(0.3-0.5)Ti-0.3Y
2O3 (in wt.)
Manufacturing route Mechanical alloying -
elemental or pre-alloyed powders Canning and
degassing of the milled powders Compaction of
the powders by HIPping Thermal-mechanical
treatments Hot pressing Hot rolling High
speed hot extrusion
Z. Oksiuta et al., MAT-ODSFSEFDA Monitoring
Meeting,Garching, January 2009
13
Refinement of the grain size using equal
channelangular pressing (ECAP) or high-speed hot
extrusion Successful trials on the EUROFER
RAFM steel Experiments will be performed on ODS
steel variants
Develop an optimised generation of
nano-structured and nano-grained ODS RAF steels
T 550C a 105C 8 passes
M.A. Auger et al., MAT-ODSFS EFDA Monitoring
Meeting, Stockholm, July 2009
14

• Investigate the stability of present and
  optimised generation of nanostructured ODS RAF
  steels under creep and irradiation

Specimens of the MA957 ODS ferritic steel in the
hot extruded and cold worked condition have been
irradiated in the SINQ facility (Swiss Spallation
Neutron Source) Doses 5-20 dpa T
115-360C 50 appm He/dpa 450 apm H/dpa
Tensile tests The irradiated MA957 ODS ferritic
steel retained a significant ductility at both
25C and 250C testing temperatures
J. Henry et al. EFDA Monitoring Meeting, July
2009
15
MAT-WWALLOYSTungsten and Tungsten Alloys
Development
16
Goals Roadmap
17

• Development of Structural Tungsten Materials
• Can the DBTT be significantly decreased?
• Is it possible to reach a compromise between
  strength, ductility, and heat conductivity?
• Can we live with a pronounced anisotropic
  micro-structure or is it necessary to produce
  isotropic structured materials?
• Optimization of Tungsten Armour Materials
• What is the optimized microstructure for fusion
  relevant thermo-mechanical load conditions?
• Is it possible to increase the crack resistivity?
• What are possible solutions for the oxidation
  problem?
• Manufacturing Parts of Tungsten Materials
• How to avoid micro-cracks?
• What alternative fabrication process could be
  suitable?
• Are there applicable reduced activation brazing
  materials for W-W and W-steel joints?
• Can mass/series production processes be applied
  to tungsten parts?
• Materials Science and Modeling
• What makes tungsten so brittle?
• Is ductilization possible besides Re addition?
• What is the influence of impurities and
  microstructure on the material behavior?
• How does tungsten behave under high neutron doses
  and after significant He/H load?

18
Structural Tungsten Materials Microstructure of
Commercial Alloys
? R. Pippan, ÖAW
19
Structural Tungsten Materials Development
Fabrication by Mechanical Alloying and Hot
Isostatic Pressing
? A. Muñoz, M.A. Auger, T. Leguey, M.A. Monge,
R. Pareja, CIEMAT/UC3M/UPM
20
Oxidation Resistant Tungsten Armor Materials
W-Si-Cr Protection Bulk Materials
Self Passivating Thin Films
W10Si10Cr after 1400 C
MA WSi2/W/Cr
quarternary alloys ? WSi3Cr10Zr5SEM of cross
section, oxidized at 1000C at different times
MA W/CrSi2
? F. Koch, C. Lenser, M. Rasinski,M. Balden,
Ch. Linsmeier, IPP
? C. García-Rosales, P. López, N. Ordás, CEIT
21
Manufacturing Parts of Tungsten Materials
Functional Gradient Material, Mass Production, EC
Layer Deposition
Gradient by Powder Metallurgy
? J.M. Missiaen, J. Schlosser, Grenoble-INP CEA
Electro-Chemical Layer Deposition
W
constantthickness on edges
Eurofer
Ni on W
? W. Krauss, N. Holstein, J. Konys, J. Lorenz, FZK
22
Materials Science and Modeling
Experiments at JANNUS etc.
Theory/Computation/Validation

• Dual and triple beam irradiation
• high dpa levels
• simultaneously with He implantation
• H / He co-implantation synergy

Object Kinetic Monte Carlo (LAKIMOCA)
? C.S. Becquart, C. Domain, U. Sarkar, M. Hou,
LMPGM Villeneuve dAscq, EDF Moret sur Loing,
Université Libre de Bruxelles
DFT Calculations He Vacancies near Surfaces
(SIESTA)

• Positron Annihilation Spectroscopy (PAS)
• Doppler broadening
• Positron Lifetime Spectroscopy

? C.-C. Fu, CEA
Ab Initio Dislocation Modeling
TEM (extended defects investigations)

• L. Ventelon, F. Willaime, M.-C. Marinica, CEA
• L. Romaner, ÖAW

Micromechanics
? R. Pippan, ÖAW
? M.-F. Barthe, P.-E. Lhuillier, T. Sauvage, P.
Desgardin, CEMHTI, CNRS Orléans, ? R. Schäublin,
EPFL, CRPP
? P. Trocellier, CEA
23
MAT-SiC/SiC SiCf/SiC Composite for Structural
Application in Fusion Reactor
24
SiC/SiC Composites for structural application
ISSUES
MAIN REQUIREMENTS
Non-porous (gas impermeability) . High
mechanical strength and reliability Low netron
activation .. High thermal conductivity
. No (low) swelling ..
High residual porosity for the most developed
processing route (CVI) SiC fibres sensitive at
high T processing Sintering additive are needed
for densification Porosity and oxide impurities
lower the l b-SiC transforms to a-SiC at high
temperatures
OBJECTIVES
Elimination / lowering porosity ? alternative
processing technique Increase in thermal
conductivity ? lower porosity incorporation
of materials with higher l (e.g. metal)
25
Processing techniques for manufacturing SiCf/SiC
CVI - Chemical vapor infiltration ? open
porosity, .. PIP - Preceramic polymer
infiltration and pyrolysis ? open porosity,
.. NITE - Nano-powder infiltration and transient
eutectoide Ceramic processing
SiO2-Al2O3-Y2O3 ? high sintering T p, Al, ..?.
SiTE - Slip-Infiltration (EPI) Transient
Eutectoide Hybrid SITE - Slip
infiltration (EPI) PIP

• E-field driven powder infiltration
• Vacuum infiltration with precursor
  SiO2-MeO-P2O5 (MeAl, Mg) / preceramic polymer
• Sintering at Tlt 1500 C / pyrolysiscrystallisat
  ion

Increase in thermal conductivity
Porosity reduction electrophoretic infiltration
to increase green density W-wires
incorporation feasibility study ?
reactivity?! CNT-coating on SiC-fibres
feasibility study
26
Increase in thermal conductivity
(W,SiC)f/SiC
lw 170 W/mK
(CNT-SiC)f/SiC
lCNT gt 2000 W/mK

• Proposed effects of CNT interphase layer on SiC
  fibers
• increase in toughness and reliability by crack
  deflection (energy dissipation)
• Increase in thermal conductivity

CNT-interphase layer on SiC fibers
K. König, S. Novak, et al, Fabrication of
CNT-SiC/SiC composites by electrophoretic
deposition, JECS, xxx (2009)