1. “Materials for Fission & Fusion Power” Steve Roberts Sergei Dudarev CCFE George Smith Gordon Tatlock Liverpool Angus Wilkinson Patrick Grant Andrew Jones Liverpool Steve Donnelly Huddersfield Sergio Lozano- Perez Michael Moody James Marrow Steve Fitzgerald Chris Grovenor Paul Bagot

2. “Materials for Fission & Fusion Power”

3. 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)?

4. Irradiation effects 1-100 displacements per atom 100’s ppm helium Transmutation radioactivity Fast neutron test reactor, hot cells …or…

5. Irradiation effects 1-100 displacements per atom 100’s ppm helium Transmutation radioactivity Fe + / W + H +, He + 2 - 30 MeV ~0.5 - 4  m Steel, Tungsten, ….

6. electrons ions

7. In-situ irradiation of Fe at 300°C Dose increment: 6~10 dpa; viewed 40 x real time 25 nm – these are interstitial loops with b = ½ [-111]

8. Oxide – Dispersion - Strengthened alloys: radiation resistance No irradiation 0.5 dpa 1 dpa 2 dpa Particles stable, and no radiation damage was visible below 1 dpa ODS PM2000, RT irradiated with 150 keV Fe+, room temperature

9. Atom-Probe: Radiation-induced clustering in Fe-Cr alloys Implanted depth ~500- 1000nm FIB “lift out” preparation (Fe not shown) 2nm thick slice Clusters Clusters only post Pt Fe-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 58nm 42 nm Fe-3at.%Cr alloy Atom probe tip 300°C, 2MeV Fe +  1dpa 1m1m

10. Hardness (GPa) Fe – x% Cr Unimplanted Low dose rate High dose rate Low dose rate High dose rate Mechanical effects: dose rate Low dose rate High dose rate At lower dose rate, Cr clusters form on dislocation loops - much greater hardening effect

11. Irradiation effects in W: Nanoindentation W+W+ 2 MeV He + W+W+ W+W+ unimplanted W+W+ He + W + +He + Hardness (GPa)

12. Micro-mechanical Testing 50  m Un-irradiated Irradiated FIB Milled Line 5  m Microcantilevers produced by Focussed Ion-Beam

13. Micro-mechanical Testing: Tungsten 20  m UnimplantedW Implanted W&He Implanted Yield Stress (GPa) 2.0 ±0.9 (4 Cantilevers) 3.1 ±0.7 (4 Cantilevers) 3.1 ±0.7 (7 Cantilevers) Fracture Toughness (MPa√m) >29 ±12 (0/2 Cantilevers) >15 ±3 (0/4 Cantilevers) 17 (1/7 Cantilevers) 1m1m

14. Active Material: Fe-6%Cr N-irradiated to 1.7 dpa at 288°C, dose rate ~1 x 10 -7 dpa/s 0.1mm FIB work at CAES, Idaho ▫ 66 cantilever beams with depths from 0.82 to 7.3 μm ▫ Also made in ▫ Ion-irradiated Fe-6%Cr, same dpa & temperature ▫ Unirradiated 1mm Activity: 37MBq

15. Neutron-irradiated Unirradiated Ion- irradiated Micromechanical testing Fe-6%Cr – yield stress

16. -100°C  +750°C World-unique Si: 500°C Si: 700°C Micro-mechanical Testing: Temperature

17. 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)