UCSB Advanced Fusion Materials Program (AMP) G. R. Odette (PI) and T. Yamamoto (Co-PI )

1. UCSB Advanced Fusion Materials Program (AMP) G. R. Odette (PI) and T. Yamamoto (Co-PI)

2. Current UCSB Performers Professor G. R. Odette (PI) Research Scientists T. Yamamoto (Co-PI) and P. Wells* PhD Research Specialist Y. Wu (TEM) Post Docs M. E. Alam and S. Pal PhD students T. Stan and N. Almirall* Development Engineers D. Gragg and K. Fields Typically two undergraduates and international visitors *Not major project – noteeveryone is multiply funded

3. Major Collaborations – Huge Leveraging • S. Maloy LANL, D. Hoelzer ORNL: NFA consortium • Y. Dai & P. Spaetig PSI: - STIP irradiations/PIE, He effects, deformation and fracture research. • X. Nagai Tohoku U/Oarai n-irradiations and PIE including PAS • A. Kimura Kyoto Univ: DuET facility dual ion irradiations • S. Tumey LLNL: CAMS 70 MeV Fe-ion facility irradiations. • D. Morgan U. Wisconsin: modeling • Y. Jiang Central South U. China: modeling. • L. Ecker BNL synchrotron X-ray characterization • Profs. Hosemann (Berkeley), Marquis and Was (Michigan) Lewandowski (CWRU) and many more faculty & lab scientists • UCSB ATR-1 international consortium with many participants Oxford, INL, LANL, ANSTO, Michigan ,…

4. UCSB Program Framework • Early assessment of potentially show stopping feasibility level issues for fusion energy materials with emphasis on He effects and predictive semi-empirical property models. • Experiments and models to better quantify alloy application windows. • Developing new alloys to solve grand challenges. • Topics: constitutive laws; He effects; embrittlement and fracture; alloy service stability and swelling; nanostructured ferritic alloys; irradiation experiments; integrated modeling

5. The M3 Fusion Materials Grand Challenge • He effects are the 800 pound gorilla facing fusion structural materials -- He/dpa (appm He/dpa): fast fission < 0.2; fusion first wall ≈ 5-20; spallation > 50 • M3 - measuring, modeling & mitigating irradiation damage in He rich environments. • Scientific challenge – understanding and modeling. • Engineering challenge - predicting and mitigating. ITER - 3 FSNT - 30 DEMO - 100 ENERGY - 200 Property Fusion high He/dpa Fission low He/dpa ???? dpa

6. 7 mm 3.4 mm 1.7 mm Adjusted What – Why – How -Where • What we are doing -- Why we are doing it (fusion impact/relevance) -- How we have contributed --Where we stand • Example -- Fast Fracture • Require crack tolerant designs but transferring coupon toughness (KJc) to complex structures is a grand challenge and standard fracture mechanics methods do not work • UCSB helped pioneer the Master Curve Method and extended it for application to small specimens - thin walled structures – irradiationdamage and He rich irradiation environments 350 Eurofer97 Measured data KJm or KJr (MPa√m) 0 Size and geometry effects

7. Linked Multiscale Models and Experiments ΔTo • Master curve mechanisms and shape • Model size and geometry effects • ΔTo = f(dpa, Ti, K', alloy, He) MC model MC model MC

8. DII DuET ISHI-HFIR Spallation protons SINQ FEA Titan TEM Imago HR3000 Laser LEAP FEA Helios Dual Beam FIB ISHI 500°C 21dpa & 1250 appm He Irradiation and Characterization Tools

9. Generate mobile He by transmutation and emission from traps Matrix transport of He partitioning and nucleation and growth of matrix cavities Grain boundaries Fine scale precipitates Dislocation substructures Other precipitates Master Model TF&C Framework Transport of He within and between interconnected sub-regions Emission of He from sub-regions Formation of sub-region cavities Internal sub-region structure

10. Kyoto U. DuET facility TMS & NFA: ≈ 407 alloy-He-dpamax-Ti conditions – some bubbles grow to convert to unstably growing voids in TMS but not in NFA • TMS incubation dpai = f(He) & post-incubation swelling ≈ 0.1%/dpa – not assumed that ions ≠ neutrons • At DII 10 He/dpa dpai ≈ 70 &700 appm He -ISHI neutron 500 appm He Higher Swelling Group 20 Dual Ion Irradiations (DII) 0.1%/dpa 10 < 5 He/dpa > 40 30

11. Why Nanostructured Ferritic Alloys • NFAs are an ODS ferritic (12-16Cr) steel variant containing an ultra-high density of nm scale oxide namo-features (NFs) imparting remarkable high strength (static, creep, fatigue) and irradiation tolerance NFs trap helium away from grain boundaries in fine bubbles & prevent swelling Fine < µm grains 1-4 nm NFs High dislocation density Thermally stable NFs provide high creep strength up to 800ºC Interface supplies trapping sites for defect recombination

12. Only bubbles, no voids in NFA at 500 & 650°C. Managing Helium in NFA

13. 3D Nanoscale Correlative Tomography and High Resolution Microscopy

14. True Stress-Strain Constitutive Laws σ(e) • Obtaining property data and transfer to structural analysis requires true stress-strain σ(ε) constitutive data and models up to high post-necking tensile strains – necking < 1% in most irradiation conditions. • Developing and applying procedures to evaluate σ(ε) and model Δσ(ε, ε', Tt, dpa, Ti, He, alloy)

15. Helium Effects on RATMS • SPI irradiations – Δσys+ He embrittlement synergisms lead to huge ΔTo & IG fracture due to weakening of GB and increased Δσys at > ≈ 500 appm He • We are refining a microstructurally and mechanism based predictive ΔTo model Low He neutron Low He neutron

16. Favorable NFA Attributes • High strength (static/creep), ductility, toughness and irradiation tolerance NFA-1 M. Toloczko ion irrad. TMS Eurofer total MA957 variants Averages uniform

17. UCSB Irradiation Experiments Helped conceive, build and implement the US-Japan HFIR irradiations beginning in ≈ 2000: 15J, 17J, JP25-29 - leading some US tasks on deformation, fracture, He effects (ISHI) and NFA with PIE on JP-25-26 and NFA UCSB ATR-1: 1.8 to 6 dpa at 300 to 750°C multi-purpose/objective to create a huge library of a variety of specimens including ISHI and diffusion multiples,… STIP V-VII: TMS and NFA over a range of temperatures at high to very high He/dpa DuET (Kyoto) dual ion irradiations 500 and 650°C to create a large database of irradiation conditions (>407) CAMS 70 MeV single ion irradiation to explore dpa, dpa rate and ion versus neutron variables on microstructure and properties 3.5 peak dpa at 300°C – 70 alloys Ni Ni 0 - 140 0 - 140 70 -140 210 appm He 140

18. PIE To Be Initiated and Proposed Irradiations Replace JP28-29 STIP V PIE initiated in FY 2017 after shipment to LANL 8/16 and proposed STIP VI recovery summer 2017. Proposed HFIR rabbits to reach higher dpa and He (ISHI) and to explore innovative "lab on a chip" studies including "boot-strap" sequential ion-neutron neutron-ion, neutron-neutron irradiations