Fundamental understanding of Nb effect on corrosion mechanisms of - - PowerPoint PPT Presentation

Fundamental understanding of Nb effect on corrosion mechanisms of Zr-Nb alloys in and out of reactor

Zefeng ng Yu Yu1, Michael Moorehead2, Leo Borrel2, Mukesh Bachhav3, Lingfeng He3, Jing Hu4 and Adrien en Couet1,2

1University of Wisconsin, Madison – Material Science and Engineering Department 2University of Wisconsin, Madison – Engineering Physics Department 3Idaho National Laboratory – Materials and Fuels Complex 4Argonne National Laboratory – Intermediate Voltage Electron Microscopy-T

andem Facility

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

2

RESEARCH

EARCH BACKGRO ROUN UND AN AND MOTIV IVATIO TION

• Irradiation effect on microstructure of ZrNb alloy:
• In-reactor irradiation induces “βNb” platelets [2].
• Proton irradiation also induces the precipitation of those platelets [3].
• Hy

Hypo pothe thesis sis: Irradi radiat atio ion reduc educes es Nb Nb conc concent entrat atio ion in in α-Zr Zr matri atrix by by pr precipit cipitat atin ing Nb Nb-rich rich ir irra radi diat atio ion-in indu duced ced pl plat atel elet ets resulting esulting in in low lower er corrosi

• sion
• n kinet

etics ics

[2] Doriot, S, et al. ASTM Special Technical Publication, vol. 1543, 2015, pp. 759–799.

1 dpa proton irradiated M5 neutron irradiated M5

[3] Verlet, Romain. Influence of Irradiation and Radiolysis on the Corrosion Rate and Mechanisms of Zirconium Alloys, 2015.

UW Environme

• nment

ntal Degr gradat dation

• n of Nuclea

ear Mater erial als s Laborato

• ratory

19th International Symposium on Zirconium in the Nuclear Industry

14 dpa

3

720 ͦC 580 ͦC

ZrNb Microchemistry Effect on Corrosion Kinetics:

• Understand how Nb distribution affect corrosion kinetics of Zr alloys.

Samples:

• 720 ͦC Zr-1.0Nb:

αZr + βZr (Fe = 750 ppm)

• 580 ͦC Zr-1.0Nb:

αZr + βNb + Laves phases (Fe = 600 ppm)

UW Environme

• nment

ntal Degr gradat dation

• n of Nuclea

ear Mater erial als s Laborato

• ratory

19th International Symposium on Zirconium in the Nuclear Industry

720 ͦC 580 ͦC

Expe pected ted microst

• struct

ructur ures es:

UNIRRA

RRADIA DIATE TED ZR-1.0N

0NB MODEL ALL

LLOY

• 1. Nb distribution and electronic structure in the oxide

4

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

CORR

RROSIO SION KINETICS ETICS OF OF ZR-1.0N

0NB

• 1. Nb distribution and electronic structure in the oxide

1. Exponent of oxidation kinetics varies from: 0.5 (720°C) → 0.36 (580°C) 2. Parabolic kinetics are typically associated with electroneutrality (and other things…) 3. Sub-parabolic kinetics can be caused by space charges (and other things…)

5

UNIRRA

RRADIA DIATE TED ZR-1.0N

0NB CHA

HARA RACT CTERI RIZA ZATION ION

• 720 ͦC Zr-1.0Nb:

αZr + βZr (highlighted in yellow)

βZr

UW Environme

• nment

ntal Degr gradat dation

• n of Nuclea

ear Mater erial als s Laborato

• ratory

19th International Symposium on Zirconium in the Nuclear Industry

• 580 ͦC Zr-1.0Nb:

aZr + βNb (highlighted in red)

BF HAADF

• 1. Nb distributio

ribution n and electronic tronic struc ructu ture e in the ox

• xid

ide

[5] M. Moorehead, Z. Yu, L. Borrel, Z. Couet, J. Hu, Z. Cai, Comprehensive Investigation of the Role of Nb on the Oxidation Kinetics of Zr-Nb Alloys, Corrosion Science (2019).

After corrosion 360 °C, 18 MPa Nb in βZr dissolves in oxide βNb remai ains ns in

• xide,

, limit ited ed Nb dissolut lutio ion

7 days Thickness: 0.86 μm 45 days Thickness: 1.8 μm

6

UNIRRA

RRADIA DIATE TED ZR-1.0N

0NB CHA

HARA RACT CTERI RIZA ZATION ION

• Microchemistry of βZr at oxide and metal interface :

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

• 1. Nb distribution and electronic structure in the oxide

[5] M. Moorehead, Z. Yu, L. Borrel, Z. Couet, J. Hu, Z. Cai, Comprehensive Investigation of the Role of Nb on the Oxidation Kinetics of Zr-Nb Alloys, Corrosion Science (2019).

• xide

metal

• Nb

Nb is is seen to to leech out fr from the β-Zr Zr precipit itat ate upo pon oxid idation tion.

• Doping

ping the oxide de with additional ditional Nb Nb in in soli lid solut ution ion

• WHAT IS

IS THE Nb Nb OXID IDATIO TION ST STATE? E?

Incident X-Ray Energy

Monochromatic X-Ray Beam X-Ray Detector Nb Kα X-Ray

• Monochromatic incident X-ray beam is

increased in energy

• Shape of the Nb Kα X-ray emission

curve can be fit to known standards using Athena

• Metallic/Oxidized fractions can then

be determined

0.2 0.4 0.6 0.8 1 1.2 1.4 18950 19000 19050 19100

Normalized Counts Incident X-Ray Energy (eV)

XANES Sample Fitting

Raw Data Data Fit NbO Powder, 2+ Nb Alloy, Metallic Nb Powder, Metallic

XANES SETU P A T TH E SYN C H ROTRO N APS

UW Environme

• nment

ntal Degr gradat dation

• n of Nuclea

ear Mater erial als s Laborato

• ratory

19th International Symposium on Zirconium in the Nuclear Industry

• 1. Nb distribution and electronic structure in the oxide

8

UW Environme

• nment

ntal Degr gradat dation

• n of Nuclea

ear Mater erial als s Laborato

• ratory

19th International Symposium on Zirconium in the Nuclear Industry

2 um

• Nb experiences delayed

layed oxi xida dation tion in comparison to the Zr matrix.

0.0% 0.2% 0.4% 0.6% 0.8% 1.0% 1.2%

• 4
• 2

2 4

Amount of Nb oxidized (wt%)

Distance from interface

Oxidation Profile Zr-1.0Nb (720C)

M/O O/W

XANES ANES DATA ANAL

ALYSIS SIS

• 1. Nb distribution and electronic structure in the oxide

9

UW Environme

• nment

ntal Degr gradat dation

• n of Nuclea

ear Mater erial als s Laborato

• ratory

19th International Symposium on Zirconium in the Nuclear Industry

• More Nb remains metallic, locked in SPPs, in 580°C Zr1.0Nb oxide

than in 720°C Zr1.0Nb oxide.

• This confirms the TEM/EDS data
• WHY DO WE CARE?

XANES RESU LTS

• 1. Nb distribution and electronic structure in the oxide

Zr-1.0Nb (720°C)

10

UW Environme

• nment

ntal Degr gradat dation

• n of Nuclea

ear Mater erial als s Laborato

• ratory

19th International Symposium on Zirconium in the Nuclear Industry

2 um

• Rationalization using the Coupled Current Charge Compensation model:
• 1D conservation law for VO

.. and 𝑓− : 𝜖𝐾𝑡 𝑦,𝑢 𝜖𝑦

+

𝜖𝐷𝑡 𝑦,𝑢 𝜖𝑢

= 0

• The interface reactions are at equilibrium.
• The diffusion of oxygen into the metal or suboxide formation ahead of the oxide are

neglected

• The oxide-water and oxide-metal interfaces are planar and the oxide microstructure

homogeneous.

• The coupled-current condition of net zero charge transport through the film at all times.

෍

𝑡 diffusing species

𝑎𝑡𝑓𝐾𝑡 = 0, 𝐾𝑡 = 2𝑏𝜉𝑡e

− 𝑓𝜂𝑡 𝑙𝐶𝑈

𝐷𝑡

𝑙−1e 𝑎𝑡𝑓𝑏𝐹𝑙 𝑙𝐶𝑈

− 𝐷𝑡

𝑙e − 𝑎𝑡𝑓𝑏𝐹𝑙 𝑙𝐶𝑈

• Local space charge at monolayer 𝑙 (hydrogen not modeled, see poster session):

𝜍𝑙 = ෍

𝑡 All species

𝑎𝑡𝐷𝑡

𝑙 = 2𝐷VO

..

𝑙 − 𝐷e− 𝑙 +

෍

𝑗 Aliovalent ions

𝑎𝑗𝐷𝑗

𝑙

• 1. Nb distribution and electronic structure in the oxide

MO D ELIN G O F NB EFFEC T O N CO RRO SIO N

11

UW Environme

• nment

ntal Degr gradat dation

• n of Nuclea

ear Mater erial als s Laborato

• ratory

19th International Symposium on Zirconium in the Nuclear Industry

2 um

• Space charge 𝝇 𝒚

→ local l ele electric ic fie field, 𝐹𝑙 :

𝐹𝑙 = 𝐹0 + 8𝜌𝑏𝑓 𝜁𝜁0 Γ

𝑙 ෍ 𝑚=1 𝑙

2𝐷VO

..

𝑚

− 𝐷e−

𝑚

with Γ

𝑙 =

1 − ෍

𝑚=1 𝑙 σ𝑛=0 5

4 − 𝑛 𝐷Nb 4−m ′

𝑚

2𝐷VO

..

𝑚

− 𝐷e−

𝑚

• Γ𝑙 is defined as the space charge compensation factor evaluated at the 𝑙th

layer.

• If Γ𝑙 = 0 ⟺ σ𝑛=0

5

4 − 𝑛 𝐷Nb 4−m ′

𝑚

= 2𝐷VO

..

𝑚

− 𝐷e−

𝑚 , then loca

cal l el electroneutrali lity is achieved thanks to the solute Nb in the oxide

• If Γ𝑙 = 0 ⟹ para

raboli lic kinetics

• Solved using a robust Newton-Raphson method.
• 1. Nb distributio

ribution n and electronic tronic struc ructu ture e in the ox

• xid

ide

MO D ELIN G O F NB EFFEC T O N CO RRO SIO N

12

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

2 um

• C4 model result:
• 1. Nb distribution and electronic structure in the oxide

MODE

DELING LING OF OF NB EFF FFECT ECT ON ON CORROS ROSIO ION

As expected, the ZrNb alloy corrosion kinetics decreases (and becomes sub- parabolic) IF LESS Nb IS IN SOLID SOLUTION to compensate the space charge

13

XANES VS C4

UW Environme

• nment

ntal Degr gradat dation

• n of Nuclea

ear Mater erial als s Laborato

• ratory

19th International Symposium on Zirconium in the Nuclear Industry

Ok… solute Nb matters for corrosion rate… Do that apply to irradiation?

• M. Moorehead, Z. Yu, L. Borrel, Z. Couet, J. Hu, Z. Cai, Comprehensive Investigation of

the Role of Nb on the Oxidation Kinetics of Zr-Nb Alloys, Corrosion Science (2019).

• 1. Nb distributio

ribution n and electronic tronic struc ructu ture e in the ox

• xid

ide

C4 model: For Nb2+: Γ𝑙 = 0 ⟺ 2𝐷Nb2′

𝑚

= 2𝐷VO

..

𝑚

− 𝐷e−

𝑚

For Nb3+: Γ𝑙 = 0 ⟺ 𝐷Nb′

𝑚

= 2𝐷VO

..

𝑚

− 𝐷e−

𝑚

XANES: ෍

𝑛=0 5

𝐷Nb𝑛′

𝑚

However, XANES is not sensitive enough for: ෍

𝑛=0 5

4 − 𝑛 𝐷Nb 4−m ′

𝑚

Zr1.0Nb (720 °C) 135 days 7 days Nb2′ Nb3′ Nb2′ Nb3′ Nb2′ Nb3′ Nb2′ Nb3′ Zr1.0N 0Nb (580 (580 °C) 7 days 135 days

14

IRRA D IATIO N EXPERIM EN TA L SETU P

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

2MeV Proton Irradiation at University of Wisconsin-Madison Ion Beam Laboratory Parameters: 8-10 μA , 1.3x1019 ions/cm2/s, 1.0 dpa, 123 hrs, 350°C

Temperature history

[4] Yu, et al. “Irradiation-Induced Nb Redistribution of ZrNb Alloy: An APT Study.” Journal of Nuclear Materials, vol. 516, 2019, pp. 100–110.

• 2. Proton irradiation induced Nb redistribution
• μ

15

(S) S)TEM/E TEM/EDS DS ON

ON UNIRRADIA IRRADIATED TED ZR-XNB

NB

• Total element composition:
• 570 ͦC Zr-0.5Nb :

αZr + β Nb + Laves phases

• 570 ͦC Zr-1.0Nb: α Zr + βNb + Laves phases

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

ppm Nb Fe Al Cr Ni Si Zr0.5Nb 5270 430 50 30 20 20 Zr1.0Nb 11270 470 40 40 20 10

• 2. Proton irradiation induced Nb redistribution

16

(S) S)TEM/E TEM/EDS DS ON

ON IRRA RRADIA DIATED TED ZR-XNB

• Irradiated samples were prepared by FIB
• Irradiation induced platelets were found in 1 dpa Zr0.5Nb

UW Environme

• nment

ntal Degr gradat dation

• n of Nuclea

ear Mater erial als s Laborato

• ratory

19th International Symposium on Zirconium in the Nuclear Industry

Fe Zr Nb Cr STEM BF

platelets + native

• 2. Proton irradiation induced Nb redistribution

17

• Irradiation induced platelets were also found in 1 dpa

dpa Zr Zr1.0Nb Nb

• Ther

ere ar are lots of

• f Nb

Nb-ri rich ch pl plat atel elet ets (ma

• max. 40

40 at at.%) fo for 1 dpa dpa Zr Zr1.0Nb Nb

135 ± 69 nm long 27 ± 12 nm wide

• UW Environmental Degradation of Nuclear Materials Laboratory

19th International Symposium on Zirconium in the Nuclear Industry

BF 30 nm

(S) S)TEM/E TEM/EDS DS ON

ON IRRA RRADIA DIATED TED ZR-XNB

• 2. Pro

roto ton n irradiatio ation n induced uced Nb re redist istributio ibution

18

AP APT CHA

HARACTERIZA TERIZATION TION

• APT study on Zr1.0Nb and Zr0.5Nb shows Nb

Nb-ri rich ch nanocluster anoclusters in in the the irr rrad adiated iated samples.

• Observation of nanoclusters are consistent with literatures.
• Proton irradiation on Low-Tin ZirloTM by E. Francis [6].
• 4MeV Ni3+ at 573K on J-AlloyTM [7] .

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

1dpa Zr0.5Nb Zr1.0Nb

[4] Zefeng Y., Couet A. (2019). JNM

[6] Francis, E., Babu, R., Harte, A., Martin, T., Frankel, R., Jadernas, D., . . . Preuss, M. (2019). Effect of Nb and Fe on damage evolution in a Zr-alloy during proton and neutron irradiation. Acta Materialia, 165, 603-614. [7] Matsukawa, Y., Yang, H.L., Saito, K., Murakami, Y., Maruyama, T., Iwai, T., . . . Abe, H. (2016). The effect of crystallographic mismatch on the obstacle strength of second phase precipitate particles in dispersion strengthening: Bcc Nb particles and nanometric Nb clusters embedded in hcp Zr. Acta Materialia, 102, 323-332.

• 2. Proton irradiation induced Nb redistribution

19

AP APT CHA

HARACTERIZA TERIZATION TION

• Nb concentration of irradiated Zr-xNb after cluster analysis

Iso-density method is used (but did max. separation as well…, same results)

• Nb concentration in the solid solution is reduced as irradiation dose

increases.

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

• 2. Proton irradiation induced Nb redistribution

20

UW Environme

• nment

ntal Degr gradat dation

• n of Nuclea

ear Mater erial als s Laborato

• ratory

19th International Symposium on Zirconium in the Nuclear Industry

2 um

• C4 model result:
• 2. Pro

roto ton n irradiatio ation n induced uced Nb re redist istributio ibution

MO D ELIN G O F NB EFFEC T O N CO RRO SIO N

As expected, the irradiated ZrNb alloy corrosion kinetics slowly decreases (and becomes more and more sub-parabolic) as less and less Nb is available to compensate the oxide space charges.

21

DEFE

FECT CT AT AT PLATEL TELET ET/M

/MATRIX

TRIX INTER TERFACE

• HRSTEM shows edge

edge disloc dislocat atio ions ns (poi (point nted whi white te arr arrows)

• ws) nearby the

two ends of irradiation induced platelets.

• Orientation relationship: 𝟑ഥ

𝟐ഥ 𝟐𝟏 𝒂𝒔// // 𝟐ഥ 𝟐𝟐 𝑶𝒄 ; (000 000ഥ 𝟑)Zr

Zr //

// (011)Nb

Nb

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

b

• 3. Nb redistribution under irradiation mechanism

22

4D 4D-STEM STEM STRAIN

AIN MAP APPING PING

• 4D-STEM plots the strain relative to the irradiated Zr matrix.
• Relatively large strain field (yellow regions) were found nearby the two

ends of platelets.

UW Environme

• nment

ntal Degr gradat dation

• n of Nuclea

ear Mater erial als s Laborato

• ratory

19th International Symposium on Zirconium in the Nuclear Industry

റ 𝑕1: റ 𝑕2:

B) C)

റ 𝑕1: matrix [000ത 2] / platelet [011] റ 𝑕2: matrix [0ത 11ത 1] / platelet [ത 101] d-spacing (A) d-spacing (A) റ 𝑕1 റ 𝑕2

A)

20 nm

• 3. Nb redistribution under irradiation mechanism

23

SCHE

HEMATIC TIC OF OF PRECIPIT ECIPITATE TE GROWTH

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

Native β-Nb Strain field Growth Recoil Dissolution Matrix Proton irradiation

+ + + +

Enhanced Nb Diffusion Zr Solute Resolution Irradiation induced point defects. Nucleation of Nb-rich platelet

24

CO N C LU SIO N

• ZrNb Microchemistry analysis :
• Nb is locked into βNb in the oxide, while Nb dissolves from βZr in the oxide.
• More Nb doping in the oxide in βZr containing alloy
• XANES shows that the main oxidation of Nb in the oxide is below 4+
• Effect on corrosion of ZrNb alloys:
• The C4 model reveals that the Nb doping can compensate the space charges:
• Space charge compensation induces faster, parabolic kinetics.
• Effect of irradiation on ZrNb microchemistry and microstructure:
• 2MeV, 350C, 1dpa, proton irradiation induces β Nb-rich platelets
• 2MeV, 350C, 1dpa, proton irradiation induces a reduction of solute Nb
• CONCLUSION: Irradiation of ZrNb results in a decrease of oxidation rate because of

radiation induced/enhanced precipitation, decreasing Nb in solid solution, providing less compensation of oxide space charges.

• Need to develop a radiation induced/enhanced precipitation mechanism to predict the Nb

solute depletion rate and evolution of space charge compensation factor.

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

UW Environ

• nme

mental al Degrad adati ation

• n of Nuclear

ar Materials rials Labora rator

• ry

19th International Symposium on Zirconium in the Nuclear Industry

THANK YOU

26

RESEARCH

EARCH BACKGRO ROUN UND AN AND MOTIV IVATIO TION

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

thickness time

[1] Motta, Arthur T., et al. “Corrosion of Zirconium Alloys Used for Nuclear Fuel Cladding.” Annual Review of Materials Research, vol. 45, no. 1, 2015, pp. 311–343.

27

ATO M IC PRO BE TO M O G RA PH Y O N ZRNB

• Nb

Nb concen centration tration in the entir ire e needles dles.

• Nb

Nb concen centrat trations ions are e acqui uired ed from m full l 31 Da peak k and deconvo nvoluted luted 46.5 Da peak k by IVAS AS .

• From

m ZrNb Nb phase e diagram, ram, the maximum mum solubili bility ty limit it of Nb Nb is 0.6 at%

• Unirradi

adiated ated needl edles es contains tains 0.3-0. 0.4 4 at% Nb. .

• Desp

spite te dose se level, el, all alloys

• ys exhibi

ibit t Nb concent centrati ration

• n

lower er than n the bulk Nb concentr centration. ation.

III. APT characterization

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

28

ATOMIC PROBE

BE TOMOGRAPHY RAPHY ON ON ZRNB

• Fe concentration

centration in the entir ire e needles les.

• A) is using

ng the front portion of 28 Da peak, ranging from 27.95 Da to 28.02 Da, to the avoid CO+ contribution. .

• B) is using

ng natural isotope of Fe at 27 Da (54Fe2+) with abundance of 5.845 %.

III. APT characterization

• There is an increa

ease se of Fe in irradiate diated d samples, ples, and rise e abov

• ve

e commonly monly accep cepted ted 0.02 at% Fe in Zr Zr solid lid solution. tion.

• Fe content is unexpectedly high.
• No obvious trend

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

29

ATO M IC PRO BE TO M O G RA PH Y O N ZRNB

• Nb

Nb concen centration tration of irrad radiated iated Zr Zr-xNb Nb after r cluster ster analysis lysis

• Max separatio

aration, n, proximit imity y histog togra ram, , iso-density density. .

• The Nb

Nb concentration centration in the solid id solution ution of irradiated radiated samples les are reduce uced, d, comparing aring to unirr rrad adiat iated ed condition ition. .

• Note:

e:

• Bar plots are after

iso-density method.

• Ref means “assumed

values”, either based

• n literature review
• r thermodynamics

prediction. Ref Ref

III. I. APT charact acteri erizat zation ion

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

30

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

• Corrosion of 1 dpa Zr1.0Nb and 1 dpa Zr0.5Nb
• Oxide thickness is measured from SEM and TEM images.
• Unexpectedly, the irradiated area has slightly higher oxide thickness than

unirradiated area. VII VIII.

• I. Post

st-irra rradi diatio ation n corrosio ion

CO RRO SIO N O F PRO TO N

IRRADIATED ZRN B

Zr1.0Nb/Zr0.5Nb 7/6 days Zr1.0Nb/Zr0.5Nb 38/37 days

31

• Native precipitates (blue arrow) were survived in 1 dpa Zr1.0Nb

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

➢ Minimum reduction of Nb concentration in native precipitates to about 60 at.%. Some of native βNb have reduced to 40 at.% or even less.

30 nm

➢ Total particle density is decreasing as dpa increases. ➢ Native precipitates were suspected to dissolve upon proton irradiation.

(S) S)TEM/E TEM/EDS DS ON

ON IRRA RRADIA DIATED TED ZR-XNB

III. I. Irradia iatio tion Experiment eriment

31

2 Mev H+ irradiation, 350ºC

32 570 ͦC Zr-0.5Nb Zr-1.0Nb

Autoclave corrosion at 260 ͦC and 6 MPa

Nb SOLU LUTE TE CONCEN CENTRAT TRATION ION DECREA CREASE SE

1 2 3

Characterization: APT/(S)TEM/EDS/XANES

PL A N TO TEST HYPOTH ESIS

4 5 6

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

33

UW Environmental Degradation of Nuclear Materials Laboratory 19th International Symposium on Zirconium in the Nuclear Industry

PRELIM IN A RY CO N C LU SIO N S:

1. Does Nb distribution and electronic structure in the oxide affect corrosion kinetics? YES!

• Microstructure indeed has an effect on Zr-1.0Nb corrosion kinetics.
• Since βZr dissolve upon oxidation, higher corrosion kinetics of Zr-1.0Nb with βZr is

suspected due to abundance of oxidized Nb, which compensated the space charge in the oxide.

Hypothesis: Irradiation reduces Nb concentration in α-Zr matrix by precipitating Nb-rich irradiation-induced platelets resulting in lower corrosion kinetics

• 2. Does proton irradiation offer a good surrogate to neutron irradiation in terms of Nb

redistribution?

• 3. What is the mechanism of irradiation induced Nb redistribution?
• 4. Does the irradiation induced microstructure of the base metal survive in the oxide

formed by subsequent corrosion?

• 5. Is the corrosion rate of pre-irradiated ZrNb samples lower than unirradiated materials

and why?

34

UW Environme

• nment

ntal Degr gradat dation

• n of Nuclea

ear Mater erial als s Laborato

• ratory

19th International Symposium on Zirconium in the Nuclear Industry

2 um

• Corrosion of 1 dpa Zr1.0Nb and 1 dpa Zr0.5Nb
• Native precipitates (yellow) remains in the oxide for 6/7 days corrosion.
• Nb-rich platelets(red) were found in oxide of 37 days corroded 1 dpa

Zr1.0Nb. Also, they were found in metal. V. Post-irradiation corrosion

CORRO

ROSION SION OF OF PR PROTON IRRADIA RADIATED TED ZRNB

Irradiated area Unirradiated BF 37 days corroded 1 dpa Zr1.0Nb

35

UNI

NIRRADI RADIATE TED SAMPL MPLE CHARA ARACTERIZA TERIZATIONS TIONS

• ST

STEM chara aracterizatio cterization of

• f unirr

rradiat adiated ed samples les

STEM showing SPPs of electropolished Zr-0.2Nb, Zr-0.4Nb, Zr-0.5Nb, Zr-1.0Nb Examples of STEM images before and after processing to identify SPPs in Zr-0.2Nb

Effect of irradiation on ZrNb corrosion mechanism

MUZIC-3 meeting EDF, 27th -29th Nov, 2018

36

UNI

NIRRADI RADIATE TED SAMPL MPLE CHARA ARACTERIZA TERIZATIONS TIONS

• ChemiST

miSTEM EM charac racter erization ization of

• f unirradiated

rradiated samples les

Effect of irradiation on ZrNb corrosion mechanism

MUZIC-3 meeting EDF, 27th -29th Nov, 2018

• For 1000°C annealed Zr-0.5Nb, there is Nb and Fe enriched lath martensites in α-

Zr matrix.

37

PRO TO N IRRA D IA TIO N O F ZRNB ALLO YS

• T

emperature is well controlled (ASTM standard)

Effect fect of irradiatio ation n on ZrNb corrosio sion n mechanism hanism

𝐹𝑒

𝑎𝑠 = 40eV

𝐹𝑒

𝑂𝑐 = 60eV

g = 6.51 g/𝑑𝑛3 Fluence = 1.4E19 ions/𝑑𝑛2

MUZIC-3 meeting EDF, 27th -29th Nov, 2018

38

• 1.0 dpa irradiated Zr-1.0Nb
• Grains remains recrystallized state. Native particles survived.
• There are multiple Nb-rich needle-like precipitates throughout the

sample at 15 μm depth from irradiation surface.

Effect fect of irradiatio ation n on ZrNb corrosio sion n mechanism hanism

CH A RAC TERIZATIO N O F 1.0 DPA ZR1.0NB

Histogram of length and width of irradiation induced needle-like precipitates. MUZIC-3 meeting EDF, 27th -29th Nov, 2018

3 µm 3 µm 3 µm

39

Effect fect of irradiatio ation n on ZrNb corrosio sion n mechanism hanism

• HRSTEM shows

Burgers orientation relationship of irradiation induced particle/matrix: (0002) // (011), [1ത 11] // [2ത 1ത 10]

(0002) {110}

Precipitate

Matrix

(0002) (0ത 111) (0ത 110) (0ത 11ത 1) (0001)

Matrix

(110) (01ത 1)

[2-1- 10]

(101)

SPP

ORIEN TATIO N REL ATIO N SH IP RIP/MATRIX

C14 – Zr [2ത 1ത 10] BCC – Nb [1ത 11]

MUZIC-3 meeting EDF, 27th -29th Nov, 2018

40

• 4-D STEM Introduction:
• Using fast electron camera,

imaging mode diffraction patterns at each scanned position are recorded at the same speed of taking HRSTEM imaging.

• By comparing d-spacings

from captured diffraction patterns with reference values, strain maps can be generated.

Effect of irradiation on ZrNb corrosion mechanism

4D S D STE TEM M ON

ON 1.0 DPA ZRNB ALL LLOYS

Muller-Caspary Knut, http://www.fz-juelich.de/er-c/er-c-1/EN/Forschung/moreSTEM/_node.html

𝜁 = 𝑑𝑏𝑞𝑢𝑣𝑠𝑓𝑒 − 𝑠𝑓𝑔𝑓𝑠𝑓𝑜𝑑𝑓 𝑠𝑓𝑔𝑓𝑠𝑓𝑜𝑑𝑓

MUZIC-3 meeting EDF, 27th -29th Nov, 2018

41

• How to generate strain map:
• 1. From 4-D STEM and HRSTEM images, diffraction patterns at each

imaging pixel size area were obtained.

Effect of irradiation on ZrNb corrosion mechanism

4D STEM O N 1.0 D PA ZRNB ALLO YS

𝜁 = 𝑛𝑓𝑏𝑡𝑣𝑠𝑓𝑒 − 𝑠𝑓𝑔𝑓𝑠𝑓𝑜𝑑𝑓 𝑠𝑓𝑔𝑓𝑠𝑓𝑜𝑑𝑓

• 2. Choose the planes of interest that

to calculated strain. For now, we use Ԧ 𝑏(0002) and 𝑐(0ത 11ത 1).

• 3. Choose the reference values.
• Method 1:

Measures the d-spacing of matrix plane using the captured diffraction patterns far away from SPP as references.

• Method 2:

Use ideal al d-spaci acing ng of matrix plane based on simulated values as references.

MUZIC-3 meeting EDF, 27th -29th Nov, 2018

42

• II. Effect of irradiation on ZrNb corrosion mechanism

MUZIC-3 meeting EDF, 27th -29th Nov, 2018

43

ATO M IC PRO BE TO M O G RA PH Y O N ZRNB

• Fe concentration in the entire needles.
• Based on literature references, Fe concentrations are acquired

from selecting a portion of the peak below 28.02 Da due to CO interference.

[5] Thuvander, & Andrén. (2011). Methods of quantitative matrix analysis of Zircaloy-2. Ultramicroscopy, 111(6), 711-714. [6] Hudson, D., & Smith, George D. W. (2011). Zirconium Oxidation on the Atomic Scale.

III. APT characterization

MUZIC-3 meeting EDF, 27th -29th Nov, 2018

dmax = 1.9 Order = 5 Nmin = 10 L = 1.5 de = L 44

MA X SEPA RATIO N METH O D

• What parameters can affect calculation?
• dmax , order , Nmin , L (set L = 0.75*dmax) , de
• Example:

Zr1.0Nb 1 dpa Fe Nb Zr

Parameter definition by IVAS manual

Identified clusters Matrix without clusters

III. I. APT charact acteri erizat zation ion

100 200 300 400 2 4

Counts distance (nm)

Nearest Neighbor Distribution

Data Random

dmax

2 4 6 8 10 6 11 16

Counts Ions

Cluster Size Distribution

data random

Nmin

MUZIC-3 meeting EDF, 27th -29th Nov, 2018

45

ISO CO N C EN TRATO N METH O D

• What parameters can affect calculation?
• Isoconce

concentra tration tion or isod

• denstiy

nstiy value ues s

• I used isoconc

concentration ntration values es

• Example:

0.6 0.8 Matrix without clusters Identify clusters Values： 1dpa Zr1.0Nb

III. APT characterization

MUZIC-3 meeting EDF, 27th -29th Nov, 2018

46

PRO XIM IT Y HISTO G RA M METH O D

• What parameters can affect calculation?
• Isoconce

concentra tration tion or isod

• denstiy

nstiy value ues

• Recommen
• mmende

ded d to use isoden densi sity ty values lues

• Requir

uired ed manual ual decomp

• mpos
• sition

ition of overla lapp pping ing peaks ks

• Exam

xample: ple:

Chose isodensity = 0.6 Create concentration profile

III. APT characterization

Averaged to get at% in solid solution

MUZIC-3 meeting EDF, 27th -29th Nov, 2018