1. IRRADIATION DAMAGE V. PONTIKIS CEA – IRAMIS – LABORATOIRE DES SOLIDES IRRADIES Matgen-iv.3 – Lerici, Sept. 19-23, 2011

2.  Modelling & experiments Defect configuration & mobility Chemical kinetics Hardening Outline Objectives To remind methodological tools that led to present knowledge about irradiation damage To emphasize on that combining experiments with theory and simulations is the key for achieving further progress Objectives To remind methodological tools that led to present knowledge about irradiation damage To emphasize on that combining experiments with theory and simulations is the key for achieving further progress  Experimental facts Swelling Phase diagrams Hardening  Elementary damage Nature of defects Healing

3. Irradiation (fast neutrons): Swelling (cf. matgen-iv-2)  Dimensional changes  Microscopic aspects  Effects of impurities 20% cold-worked SS-316 T=510 °C, D≈80 dpa  Dimensional changes  Microscopic aspects  Effects of impurities  Dimensional changes  Microscopic aspects  Effects of impurities Cu containing 105 ppm at implanted oxygen irradiated with Cu ions. F =0.003 dp/s, 3hr, annealed 30 mn T=700 °C, TEM Glowinski & Fiche, JNM (1976) 19Cr-4Al ODS ferritic/martensitic 9Cr-martensitic (a), (c) unirradiated (b), (d) 60 dpa, T=773 K After Kimura et al. (2006)

4. Irradiation: Phase Diagram (cf. matgen-iv.1) Ni(Si (4%) Ni 3 Si Ni(Si) + Ni 3 Si Ni(Si) Ni Si A. Barbu and A.J. Ardell, Scripta Metall. 9 (1975) 1233 TEM DF

5. Irradiation: Hardening & Embrittlement (cf. Matgen- iv.2) Cu clusters on dislocations (Soneda, MATGEN-IV.1) Elongatio n - Baseline - Irradiated Load 0 50 100 150 200 250 -200-1000100200300 Temperature (°C) Energy (J) baseline irradiated DBTT shift (41 J level) USE drop

6. Nuclear reactions (  a ) – (n,p) – (n,2n)  He production Irradiation: Elementary interactions Transfer of recoil energy if T>T d  Frenkel pair creation (vacancy-interstitial) Nuclear reactions: examples 10 B + n  7 Li + a, 17 O + n  14 C + a 14 N + n  14 C + p, 7 Be + n  7 Li + p 7 Be + n  2 a + 2n

7. Irradiation: Atomic scale damage Maximum energy transfer: The primary damage: Cascades & their structure Time scales Displacement threshold & the formation of stable Frenkel pairs, n F =f( a,b, T, E) (KP, Kinchin & Pease, Rep. Prog. Phys. 18 (1955) 1 ) but: KP overestimates the damage and linearity is questionable (SRIM, …) ( Lucasson, in Fundamental Aspects of Radiation Damage in Metals, Springfield, ORNL (1975) p. 42) Time-evolution of the damage: recombination & association of FP Influence of impurities and structural defects (dislocations, grain boundaries, …)

8. Irradiation: Time scales

9. Irradiation: Displacement threshold Jung, Atomic Collisions in Solids, Plenum (1975) 87 Jung, Radiat. Eff. 35 (1978) 155

10. Interstitials: Simulation I (a) Formation, Stability, Relaxations Tetra- and octahedral sites are unstable The split interstitial is of lowest energy fcc Cu {100} – E 100 (4.45 eV) * bcc Fe {110} E 110 (3.64 eV) < E 111 (4.34 eV) <E 100 (4.64 eV) ** *Le Petitcorps 2011 (CEA, unpublished) **CCF et al. Phys. Rev. Lett., 92 (2004) 175503 __________________________ Long-range relaxations R>3 th NN

11. Frenkel pairs: Simulation II (b) FP annihilation in Cu (TB) * E f ≈ 4.45 eV (exp ** : 2.5 – 5.8 eV) E m ≈ 0.11 eV Vacancy: E m ≈ 0.7 eV _________________________________________________________________ * Le Petitcorps 2011 (CEA, unpublished) ** Wollenberger, in Physical Metallurgy (Elsevier, 1983) At low T vacancies are immobile

12. Interstitials: Simulation III - Thermal migration in Cu (TB) * *Le Petitcorps 2011 (CEA, unpublished) __________________________

13. Irradiation-modified physical properties I (experiments) Aim:Measuring values of physical parameters associated with irradiation defects and predicting damage as a function of: T, E, F, F. t Difficulty:Interstitials (FP) are NOT thermal equilibrium defects and d p/defect is unknown Methodology & the analogy (damage recovery – chemical reaction) A(I)+B(V)  AB(0), if c AB is known change c B and gain knowledge on c A via isothermal and isochronal annealing experiments Budin & Lucasson, X th colloque de Métallurgie, CEA-Saclay (1965) p. 228

14. Irradiation-modified physical properties II (experiments) Assuming the kinetics is second order: A. Post-irradiation isothermal annealing with/without prior quenching

15. Irradiation-modified physical properties III (experiments) B. Post-irradiation isochronal annealing with/without prior quenching: T=A. t Validity conditions: 2 nd order kinetics C v0 =C V0 quench

16. Damage thermal evolution: Resistivity experiments I I A I B Collapse of close FP I C I D Correlated recombination I E Uncorrelated recombination II Clustering, interstitial loops III Vacancy mobility, clustering, vacancy loops & recombination IV Vacancy loops dissociation

17. Stable interstitials: Experiments – elastic constants Cu single crystal neutrons Holder et al., Phys. Rev. B10 (1974) 349, 363

18. Interstitial migration: Anelastic relaxation Al-I Spiric et al., Phys. Rev. B 15 (1977) 672, ibid. 679 Stress removal: Coupling between the external stress & elastic dipoles  reorientation

19. Interstitial migration: Anelastic relaxation Al-II s // {111} Spiric et al., Phys. Rev. B 15 (1977) 672, ibid. 679

20. Defect reactions I: Rate equations I. Low T 1 irradiation  C 0 FP – II. Heating up to T 2 triggers SIA mobility & recombination

21. Defect reactions II: Rate equations – steady state  Void growth: Brailsford & Bullough, J. Nucl. Mater. 44 (1972) 121 (swelling) Heald & Speight, Acta Metall. 23 (1975) 1389  Irradiation creep: Heald & Speight, Philos. Mag. 29 (1974) 1075 Wolfer & Askin, J. Appl. Phys. 47 (1976) 791 Bullough & Willis, Philos. Mag. 31 (1975) 855

22. Defect association I Clusters (complex defects, voids, …) Dislocations (loop growth) Precipitates

23. Defect association II: Experiments (T & F t effects) Mo, T=1150 K 1.0 dpa 1.6 dpa 2.0 dpa Igata et al., in Effects of Radiation on Structural Materials, ASTM (1979) p. 12 Interstitial loop growth, Kiritani et al. J. Phys. Soc. Japan, 38 (1975) 1677.

24. Interactions Defects - Dislocations: Hardening I Size (W≈0.1-0.3 eV/at Modulus (≈few 10 -2 eV/at vacancy ≈0.3 eV/at Dipolar (few 10 -3 eV/at) Chemical (strong) Friedel, Dislocations (1964) Osetsky & Bacon (2004) Cu clusters on dislocations (Soneda, MATGEN-IV.1)

25. Interactions Defects - Dislocations: Hardening II Al-3.5% Cu A535 °C16 hr B190 °C3 days C350 °C2 days A: solid solution - B: GP zones - C: Precipitates  L ≈≈  L

26. Towards non-equilibrium Phase-Diagrams ? Adda et al., Thin Solid Films, 25 (1975) 107Ni-Si, Barbu et al., J. Appl. Phys. (1980)

27. Conclusive remarks  Structural materials are multicomponent  complexity  Crucial need of experiments  Brute force computing cannot replace understanding and model experiments  Understanding and engineering approaches should run in parallel Simulations are NOT Experiments (Mathematics≠Physics)

28. MATGEN – IV.3, September 19-23, 2011 / Lerici, Italy Thank you for listening