“Materials for Fission & Fusion Power”
Steve
Roberts
Angus
Wilkinson
Sergei
Dudarev
CCFE
Patrick
Grant
George
Smith
Gordon
Tatlock
Liverpool
Andrew
Jones
Liverpool
Steve
Donnelly
Huddersfield
Sergio
LozanoPerez
Michael
Moody
James
Marrow
Paul
Bagot
Chris
Grovenor
Steve
Fitzgerald
“Materials for Fission & Fusion Power”
MFFP: Hot topics
• ODS alloy processing
– Microstructural development
– Joining
– Novel processing
• Small-scale <-> large scale mechanics
–
–
–
–
•
•
•
•
plasticity and fracture; temperature effects
“pure” materials
Dispersion strengthened materials
Radiation damaged materials
Alloy stability under irradiation
Crack chemistry and fracture
Helium and radiation damage
Neutrons  Ions ( Protons)?
Irradiation effects
1-100 displacements per atom
100’s ppm helium
Transmutation radioactivity
Fast neutron
test reactor,
hot cells
…or…
Irradiation effects
1-100 displacements per atom
100’s ppm helium
Transmutation radioactivity
~0.5 - 4 mm
H+ , He+
2 - 30 MeV
Fe+ / W+
Steel,
Tungsten,
….
electrons
ions
In-situ irradiation of Fe at 300°C
25 nm
Dose increment: 6~10 dpa; viewed 40 x real time
– these are interstitial loops with b = ½ [-111]
Oxide – Dispersion - Strengthened alloys: radiation resistance
No irradiation
1 dpa
Particles stable, and no radiation damage was visible below 1 dpa
ODS PM2000, RT irradiated with 150 keV Fe+, room temperature
0.5 dpa
2 dpa
Atom-Probe:
Radiation-induced clustering in Fe-Cr alloys
Atom probe tip
300°C, 2MeV Fe+  1dpa
Fe-Cr alloy
Implanted
depth ~5001000nm
•
FIB “lift out”
preparation
Pt
post
1mm
(Fe not shown)
Fe-3at.%Cr alloy
•
Cr clustering observed in
Fe-3%Cr
(associated with C)
•
Fe-3%Cr should be
STABLE according to
equilibrium phase diagram
•
Cr clusters produce
hardening and
embrittlement
Clusters only
2nm thick slice
Clusters
58nm
42 nm
Mechanical effects: dose rate
High dose rate
Low dose rate
Hardness (GPa)
Low dose rate
High dose rate
High dose rate
Unimplanted
Fe – x% Cr
At lower dose rate, Cr clusters form on dislocation loops
- much greater hardening effect
Low dose rate
Irradiation effects in W: Nanoindentation
unimplanted
He+
He+
2 MeV
W+
Hardness (GPa)
He+
W++He+
W+
unimplanted
W+
W+
He+
Micro-mechanical Testing
Irradiated
5 mm
Un-irradiated
50mm
Microcantilevers
produced by
Focussed Ion-Beam
Micro-mechanical Testing: Tungsten
1mm
20mm
Unimplanted W Implanted
W&He
Implanted
(GPa)
2.0±0.9
3.1±0.7
3.1±0.7
(4 Cantilevers)
(4 Cantilevers)
(7 Cantilevers)
Fracture
Toughness
>29±12
>15±3
17
Yield Stress
(MPa√m)
(0/2 Cantilevers) (0/4 Cantilevers) (1/7 Cantilevers)
Active Material: Fe-6%Cr
N-irradiated to 1.7 dpa at 288°C, dose rate ~1 x 10-7 dpa/s
1mm
0.1mm
Activity: 37MBq
▫ 66 cantilever beams with depths from 0.82 to 7.3μm
▫ Also made in
▫ Ion-irradiated Fe-6%Cr, same dpa & temperature
▫ Unirradiated
FIB work at CAES, Idaho
Simple
YieldFe-6%Cr
Stress
Micromechanical
testing
– yield stress
7.00E+09
Neutron Irradiated
Ion Irradiated
6.00E+09
Un-Irradiated
Ionirradiated
Yield Stress (Pa)
5.00E+09
4.00E+09
Power (Neutron Irradiated)
Power (Ion Irradiated)
Power (Un-Irradiated)
3.00E+09
2.00E+09
1.00E+09
0.00E+00
0.000
1.000
2.000
3.000
4.000
5.000
Beam Depth (μm)
6.000
7.000
8.000
Micro-mechanical Testing: Temperature
Si: 500°C
Si: 700°C
-100°C  +750°C
World-unique
Oxford Nuclear Materials: Capabilities
• Electron Microscopy
– Defects & damage
– Chemical microanalysis
– In-situ with ion-beam,
heating
• Atom-probe
tomography
– Atomic-scale chemistry
• Focussed ion-beam
sectioning
– Selected local areas for
EM and APT
• Small-scale mechanics
– Small active specimens
– Thin ion-irradiated layers
– -100°C to +750°C
• Modelling (with CCFE)
– Defects
– Mechanics
– Transmutation paths
• Links to “radiation-effects”
projects internationally
– NNUF
– NEUP/IRP
– (FAFNIR), (TRITON)