“Materials for Fission & Fusion Power”

1. “Materials for Fission & Fusion Power” SergioLozano-Perez Michael Moody James Marrow Steve Roberts SergeiDudarevCCFE George Smith Gordon TatlockLiverpool SteveFitzgerald Paul Bagot Chris Grovenor Angus Wilkinson Patrick Grant AndrewJonesLiverpool SteveDonnellyHuddersfield

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 ~0.5 - 4 mm H+ , He+ Steel,Tungsten,…. 2 - 30 MeV Fe+ / W+

6. electrons ions

7. 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]

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

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

10. 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

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

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

13. Micro-mechanical Testing: Tungsten 1mm 20mm

14. Active Material: Fe-6%Cr • N-irradiated to 1.7 dpa at 288°C, dose rate ~1 x 10-7dpa/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

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

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

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)