Mechanisms of Hydride Reorientation in Zircaloy-4 Studied In-Situ

Transcription

1 Mechanisms of Hydride Reorientation in Zircaloy-4 Studied In-Situ 500 µm K. B. Colas 1 *, A. T. Motta 1, M. R. Daymond 2, J. D. Almer 3, 1. Department of Mechanical and Nuclear Engineering, Penn State University, University Park, PA USA * Now at CEA-Saclay, France, DEN/DANS/DMN/SEMI/LM2E 2. Department of Mechanical and Materials Engineering, Queen s University, Kingston, ON, Canada 3. Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA ASTM 17 th Symposium on Zirconium in the Nuclear Industry. Feb 2-7, Hyderabad, India

2 Hydrides can dissolve and reorient under certain temperature and stress conditions Hydrides formed under no applied load Normal direction Transverse direction Hydrides formed under tensile applied load σ σ Temperature and stress (and cycling) 02/07/13 2

3 Motivation of study Mechanistic understanding of hydride reorientation important for nuclear industry Most studies on hydride precipitation done post-facto Goal: Use Synchrotron Radiation to study hydride precipitation under stress and get a better understanding of reorientation in-situ 1. Dissolution and Precipitation Kinetics: Peak Area 2. Elastic strains: Peak Position 02/07/13 3

4 In-situ experimental set-up Hydride dissolution and precipitation APS-Argonne Zr peaks Hyd peaks TD integration slice Area detector RD integration slice TD RD RD TD ND initial hydride platelets Temperature Cooling under load Cold-Worked Stress-Relieved Zircaloy µm reoriented hydride platelets 80 kev X-ray beam 02/07/13 4

5 Data analysis Transverse direction planes Rolling direction planes Raw data Diffraction patterns ASTM 17th Symposium on Zirconium in the Nuclear Industry. Feb 2-7, Hyderabad, India 5

6 Example of diffraction pattern for full ring integration at 30 C (logarithmic scale) [H] = 530 wt.ppm Zr (11.0) Delta (220) Zr (10.2) Zr (Cr 2 Fe) Delta (200) Zr (10.1) Zr (00.2) Zr (10.0) Delta (111) Deltahydride ZrH x with x~1.66 Colas KB et al. In situ study of hydride precipitation kinetics and re-orientation in Zircaloy using synchrotron radiation. Acta Mater (2010), doi: /j.actamat

7 Hydride microstructure after reorientation thermo-mechanical cycle 230 MPa stress Hydride reorientation 200 µm 7

8 1. In-situ Study of Kinetics of Hydride Dissolution and Precipitation 02/07/13 ASTM 17th Symposium on Zirconium in the Nuclear Industry. Feb 2-7, Hyderabad, India 8

9 Kinetics of dissolution and precipitation can be accurately studied with XRD 02/07/13 Colas KB et al. In situ study of hydride precipitation kinetics and re-orientation in Zircaloy using 9 synchrotron radiation. Acta Mater (2010), doi: /j.actamat

10 Hysteresis effect between dissolution and precipitation: effect of hydride nucleation δ{111} hydride peak intensity Hydrides not fully dissolved at 410 C Sample with 246 wt.ppm of H 02/07/13 ASTM 17 th Symposium on Zirconium in the Nuclear Industry. Feb 2-7, Hyderabad, India 10

11 Reoriented hydrides precipitate at a lower temperature No Reorientation Reorientation 200 μm 200 μm 0 MPa MPa 230 MPa Tp below unstressed value when hydrides reorient 11

12 2. In-situ study of elastic zirconium and hydride strains during growth and precipitation 02/07/13 ASTM 17th Symposium on Zirconium in the Nuclear Industry. Feb 2-7, Hyderabad, India 12

13 Elastic strains in zirconium matrix due to H in solid solution (α{10.0} diffraction peak) Elastic strain: ε = (d-d 0 )/d 0 (x10-3 ) Cooling Tprecip from peak intensity Heating Zr thermal expansion α Zr <a>: -Measured in TD in CWSR Zircaloy-4: 6.2 x 10-6 C -1 -Literature single crystal Zr (Goldak, Phys. Rev., 1966): 5.5 x10-6 C -1 02/07/13 ASTM 17 th Symposium on Zirconium in the Nuclear Industry. Feb 2-7, Hyderabad, India 13

14 Elastic strains in hydride δ{111} dissolved and precipitated without applied stress (x10-3 ) 14

15 Strains in zirconium matrix under applied stress (α{10.0} diffraction peak) Lower Tp Stress off Stress on 02/07/13 ASTM 17 th Symposium on Zirconium in the Nuclear Industry. Feb 2-7, Hyderabad, India 15

16 Elastic strains in hydride δ{111} precipitated with high applied stress: Reorientation Hydride face in tension 02/07/13 ASTM 17 th Symposium on Zirconium in the Nuclear Industry. Feb 2-7, Hyderabad, India 16

17 Tensile strain in TD are related to total fraction of reoriented hydrides TD ND 500 μm reference 17

18 Peak Position Summary Diffraction peak position allows us to follow zirconium and hydride elastic strain during cool-down Hydride strain behavior during precipitation under no applied stress studied: Nucleate as highly compressed particles Average strain decreases then follows thermal expansion of zirconium matrix Reoriented hydride strain behavior different than unstressed hydrides: Tensile strain in hydride platelet face Constant strain during cool-down 02/07/13 ASTM 17th Symposium on Zirconium in the Nuclear Industry. Feb 2-7, Hyderabad, India 18

19 Conclusions Hydride dissolution and precipitation has been studied in-situ We can obtain detailed information on hydrides as they precipitate Volume fraction precipitated Magnitude and range of hydride elastic strain Stress significantly affects hydride formation Leads to more radial hydride microstructure Lowers precipitation temperature Affects hydride elastic strains In-Situ XRD brings insight on mechanism of hydride precipitation and reorientation 02/07/13 ASTM 17th Symposium on Zirconium in the Nuclear Industry. Feb 2-7, Hyderabad, India 19

20 THANK YOU 02/07/13 ASTM 17th Symposium on Zirconium in the Nuclear Industry. Feb 2-7, Hyderabad, India 20

21 References Lemaignan, C. and A.T. Motta, Zirconium Alloys in Nuclear Applications, in Materials Science and Technology, A Comprehensive Treatment, R.W. Cahn, P. Haasen, and E.J. Kramer, Editors. 1994, VCH: New York. p Coleman, C.E. and D. Hardie, The hydrogen embrittlement of [alpha]-zirconium--a review. Journal of the Less Common Metals, (3), p Racine, A., Influence de l'orientation des hydrure sur les modes de deformation, d'endommagement et de rupture du Zircaloy-4 hydrure, in Mecanique et Materiaux. 2005, Ecole Polytechnique: Palaiseau, France Westlake, D.G., The habit planes of zirconium hydride in zirconium and zircaloy. Journal of Nuclear Materials, (2), p Chung, H.M., R.S. Daum, J.M. Hiller, and M.C. Billone. Characteristics of hydride precipitation in spent-fuel cladding. in Zirconium in the Nuclear Industry: 13th International Symposium. 2002: ASTM STP 918, p McMinn, A., Darby, E.C., Schofield, J.S., The Terminal Solid Solubility of Hydrogen in Zirconium Alloys. Zirconium in the Nuclear Industry: Twelfth International Symposium, ASTM STP 1354, p Eadie, R.L. and C.E. Coleman, Effect of stress on hydride precipitation in zirconium-2.5% niobium and on delayed hydride cracking. Scripta Metallurgica, (11), p Hardie, D. and M.W. Shanahan, Stress reorientation of hydrides in zirconium-2.5% niobium. Journal of Nuclear Materials, (1), p Kerr, M., M.R. Daymond, R.A. Holt, J.D. Almer, and S. Stafford, Observation of growth of a precipitate at a stress concentration by synchrotron X-ray diffraction. Scripta Materialia, (6), p Singh, R.N., R. Kishore, S.S. Singh, T.K. Sinha, and B.P. Kashyap, Stress-reorientation of hydrides and hydride embrittlement of Zr-2.5 wt% Nb pressure tube alloy. Journal of Nuclear Materials, (1), p Kim, Y.S., Y. Perlovich, M. Isaenkova, S.S. Kim, and Y.M. Cheong, Precipitation of reoriented hydrides and textural change of [alpha]-zirconium grains during delayed hydride cracking of Zr-2.5%Nb pressure tube. Journal of Nuclear Materials, (3), p Ma, X.Q., S.Q. Shi, C.H. Woo, and L.Q. Chen, Effect of applied load on nucleation and growth of [gamma]-hydrides in zirconium. Computational Materials Science, (1-4), p Colas, K.B., Kinetics of Zirconium Hydride Precipitation and Reorientation Studied Using Sychrotron Radiation, in Department of Nuclear Engineering. 2009, The Pennsylvania State University 02/07/13 ASTM 17th Symposium on Zirconium in the Nuclear Industry. Feb 2-7, Hyderabad, India 21