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November 5-8, 2013 Vienna, IAEA

Solute clustering in RPV steels under irradiation

P. Pareige, B. Radiguet, C. Pareige and A. Etienne

Groupe de Physique des Matériaux - UMR CNRS 6634 Université et INSA de Rouen

Saint Etienne du Rouvray, France

Degradation of primary components of pressurised water cooled nuclear reactors:

Current issues and future challenges

RPV steels under irradiation

Neutron irradiation

T ~ 290°C ~ 0.7×1015 m-2.s-1

embritlement

hardening

Origin : Point defects and their clusters, solutes/impurities and their clusters/precipitates, segregations (interfaces, boundaries, …), …

Vessel steel in commercial reactor

Atom Probe Tomography observations

P Si Mn Ni Cu 52×52×135 nm3

Segregation along dislocation

Solute cluster

51×51×96 nm3

P Si Mn Ni Cu Fe

Objects Cluster (Matrix)

Cluster (Dislocation)

Dislocation

P 0,11 ± 0,06 0,76 ± 0,14 0,53 ± 0,12

Si 8,84 ± 0,54 6,92 ± 0,41 6,10 ± 0,40

Mn 5,60 ± 0,44 8,10 ± 0,45 5,85 ± 0,40

Ni 10,76 ± 0,59 9,69 ± 0,48 7,20 ± 0,40

Cu 0,34 ± 0,11 0,40 ± 0,10 0,27 ± 0,08

Radius 1,4 1,5 -

Density (1022m-3)

9.2 ± 1.3 -

H. Huang, B. Radiguet, P. Pareige P. Todeschini C. Chainasse, F. Clémendot

Join Laboratory EDF / CNRS EM2VM

Different vessel steels of commercial reactors

Understanding basic mechanisms

Link microstucture and properties

Vacancy cluster (MFVIC)

y = 0,4x + 1,3

y = 1,3x - 1,3

y = 4,0x - 5,5

y = 3,9x - 4,9

0

6

12

18

24

30

1 2 3 4 5 6 7 8 9

Neutron fluence (1023

n m-2

)

Nu

mb

er

De

ns

ity

(1

022 m

-3)

Steel A (0,03 Cu) Steel B (0,044 Cu)

Steel C (0,07 Cu) Steel D (0,07 Cu)

Linear (Steel A) Linear (Steel B)

Linear (Steel C) Linear (Steel D)

0,5

1

1,5

2

2,5

0 1 2 3 4 5 6 7 8 9

Neutron fluence (1023

n m-2

)

Ra

diu

s (

nm

)

Steel A Steel B

Steell C Steel D

Steel P1 Steel F1

Steel F2 Steel F3

Cu

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November 5-8, 2013 Vienna, IAEA

Vessel steels in commercial and test reactors 5

Steel C P Si Mn Ni Cu Cr Mo V

16MND5

EDF2

(MB) 0.64 0.011 0.43 1.33 0.65 0.056 0.21 0.31 -

EDF3

(WM) 0.25 0.016 0.69 1.43 0.61 0.029 0.021 0.33 0.004

A533B FZD1a

(JPB) 0.92 0.036 0.47 1.31 0.70 0.024 0.18 0.33 0.005

15Kh2MFA AEK1

(BM) 0.74 0.032 0.57 0.54 0.066 0.078 2.82 0.39 0.30

15Kh2NMFAA NRI1

(WM) 0.32 0.011 0.73 0.75 1.59 0.035 1.99 0.40 -

Bulk composition (at.%)

Steel T (°C) Flux

(1012 cm-2·s-1) Fluence

(1019 cm-2)

EDF 3 286 0.15 - 0.2

1.26 / 3.86 / 5.13

EDF 2 1.71 / 5.22 / 6.95

FZD 1a 255 2.2 5.7

AEK 1 272-276°C ~ 2 18.3 / 90.6

NRI 1 288 ~ 30 2.1 / 4.5 / 9.5

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November 5-8, 2013 Vienna, IAEA

EDF samples 6

- Solutes (Mn, Ni, Si , Cu, P) clusters located in the matrix or along dislocation lines (all EDF steels, all fluences)

- Continuous segregation of the same elements along dislocation lines (all EDF steels, all fluences)

Irradiated conditions (EDF-2 and EDF-3 / t1 - t2 - t3)

EDF-2 / t3

One segregation on a loop ?

~1021m-3

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November 5-8, 2013 Vienna, IAEA

FZD-1 samples 7

Irradiated condition (t1)

- P segregation along dislocation lines

P

P Si M

n Ni F

e

41 × 41 × 180 nm3

- Solute clusters

Ni: 6.9±0.3 Mn: 6.8±0.3 Si: 3.0±0.2 P: 0.35±0.1 Cu: 0.07±0.03

N = 24.3±2.0×1022m-3 R = 1.0±0.2 nm

at.%

Intergranular/lath segregation on

boundary with twist component (?)

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November 5-8, 2013 Vienna, IAEA

AEK-1 samples 8

Irradiated conditions (t1 , t3) - Intergranular/lath segregation (t1)

Low angle (?) High angle (?)

θ ~ 2°

Strong influence of GB nature

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November 5-8, 2013 Vienna, IAEA

AEK-1 samples 9

Irradiated conditions (t1 , t3)

- Solute clusters (both fluences)

4,2×17×5,1 nm3

Si P Mn Ni Cu Cr C V Mo Fe

(b) (c) At carbides/ferrite interfaces

In the ferritic matrix

Along dislocation lines

- Continuous segregations (both fluences)

Along dislocation lines

Around dislocation loops

3,7×5,2×3,3 nm3

Along dislocation loops

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November 5-8, 2013 Vienna, IAEA

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Grain / lath boundaries

- Enrichment in C, Si, P, Cr, Mn, Ni, Mo often observed - Evidence of the influence of boundary nature on segregation - No clear evidence of irradiation effects

Solute clusters

- No clear trend with fluence - Flux effect

- Increase with fluence - T effect

Experiment on model alloy: solute behavior?

Fe-1%Mn

• Both alloys prepared by levitation casting

• Homogenization treatment:

1h @ 1000°C

24h @ 840°C

Air quenched

Tem

pera

ture

(°

C)

at.% Mn

Un-irradiated samples

• Random solid solution at nm-scale

• Homogeneous at µm-scale (EPMA analysis)

(0.93±0.03) at.% Mn Fe-Mn 0.5 dpa Dose

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

0,0007

0 500 1000 1500 2000 2500

Depth (nm)

dp

a/s

Homogeneous damage

Fe5+ 10 MeV

T = 400°C

3.11015 m-2.s-1

Needle thickness

11

Mn 30.8 ± 2.7

Fe 69.2 ± 2.7

Cluster composition

(at.%)

Tem

pera

ture

(°

C)

at.% Mn

( Fe, Mn)

Bulk composition Mn cluster composition

Clusters have the composition predicted by phase diagram @ 400°C in a super saturated FeMn alloy

FeMn alloy irradiated at 0.5 dpa

Radius (nm) Density (m-3)

1.5 ± 0.2 (4.8 ± 1.4).1022 Fe

Mn

8×8×8 nm3

Formation of Mn rich clusters

12

FeMn alloy irradiated at 0.5 dpa

50×50×80 nm3

30×30×150 nm3

Heterogeneous nucleation

Mécanisme interstitiel

I V

Planar defect = point defect sink

V / I flux Mn flux

Local enrichment in Mn

On point defect sink:

CMn > Mn solubility limit

Radiation induced precipitation

of Mn rich phase

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Fe-Cr alloys with different Cr content:

Fe - 2.5 at.% Cr

Fe - 4.9 at.%Cr

Fe - 8.9 at.%Cr

Fe - 12.3 at%Cr

Fe Bal.

Cr 4.61 ± 0.02

Si 0.059 ± 0.002

Ni 0.034 ± 0.002

P 0.013± 0.001

Fe Bal.

Cr 9.16 ± 0.04

Si 0.065 ± 0.003

Ni 0.057 ± 0.003

P 0.013 ± 0.001

Fe Bal.

Cr 11.2 ± 0.04

Si 0.18 ± 0.01

Ni 0.07 ± 0.01

P 0.025 ± 0.002

As measured with Atom-Probe Tomography (APT) – in at.%

Fe Bal.

Cr 2.21 ± 0.01

Si 0.020 ± 0.001

Ni 0.040 ± 0.001

P 0.0090 ± 0.0005

Intra-granular segregation and precipitation in neutron irradiated

Fe-Cr- Si,Ni impurities alloys

Dose : 0.6 dpa

Neutron flux: 9∙1013 n/(cm2 s)

Temperature: 300ºC

BR2 reactor (SCK·CEN) –

MIRE-Cr irradiation program

Calphad

Bonny et al.

a

a + a'

14

Fe-5%Cr

33×

33×

13

0n

m3

Fe-9%Cr

Cr enriched clusters

NiSiPCr enriched cluster

Fe-12%Cr

Fe-2.5%Cr

54×

54×

13

7n

m3

Two independent families of clusters are revealed 15

Fe - 9%Cr

30×30×100nm3

Fe - 12%Cr

52×52×230nm3

Cr

Si

Fe - 9%Cr

Twist grain boundary Low angle tilt grain boundary

High angle grain boundaries

Segregation of Si

16

▲ résilience KCV à 320°C ; × résilience KCU à 20°C ; ♦ dureté Vickers HV30.

Tservice (285°C – 323°C)

1 mm

40 m

C Cr Ni Si Mo Mn Fe

< 0,2 18 to 21 9 to 12 < 3 1,1 to 1,3 < 1,5 balance

What about solute behavior in Duplex Stainless Steel?

Chemical

composition % at.

Aciers Duplex

Austenite

Ferrite : 10 à 30 %

Décomposition de la ferrite : α → α + α’

α : iron rich ferritic phase

α’ : chromium rich ferritic phase

17

Kinetic

Duplex stainless steels (DSS)

2

Ferrite decomposition during ageing

V = 15 5 47 nm3

Fe rich α zones

Cr rich α’ zones (threshold XCr> 26%)

G phase enriched

in Ni, Si, Mn and Mo

(threshold XNi+XSi+XMn

>20%)

Spinodal decomposition + Precipitation

Mechanical properties

Phase transformations

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Duplex stainless steels (DSS)

Spinodal decomposition Precipitation

Synergy between spinodal decomposition and precipitation

Slope = 0.16

Slope = 0.07

Slope = 0.15

Slope = 0.06

3

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November 5-8, 2013 Vienna, IAEA

20 Summary Solutes and Impurities in BCC Iron : segregation and clustering or precipitation With Thermodynamic and/or point defects kinetics Structural evolution in RPV steels is at very beginning in comparison to other materials in other conditions… what will be the evolution of clusters?

1 dpa = 10 highest RPV exposure

Need of experiments/modelling

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Equipment of Excellence

GENESIS

Groupe d'Etude et de Nano-analyses des EffetS

d'IrradiationS

Head of the project

P. Pareige (GPM - Rouen)

C. Pareige, A. Etienne, B. Radiguet

P. Yvon (CEA DEN/DMN - Saclay)

S. Bouffard (CIMAP - Caen)

Partners

Group for Studies and Nanoanalyses of Irradiation Effects

21

22

GENESIS: International

Research Plateform

Glasses Ceramics

Non active

Metals Glasses Ceramics

Activity up 200 MBq

Metals

Highly active Hot cells

Caen Rouen Saclay

Fondamental / Applied researches, International Platforme,

Education

22

23

TEM « Station »

Dual Beam – SEM/FIB Atom Probes

EBSD 3D-FIB GIS/ micromanip.

Laser and electric mode High pulse rate High mass resolution

STEM BF / ADF / HAADF EDS / EELS / EFTEM

Double tilt/rotation specimen holder + others

specific holders

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Space

1 nm 1m

Time

1 s

1 ps

40 nm

Atoms

Electrons

Electronic structure

Ab initio (DFT-LDA)

Dislocations Dynamics (DD)

Object or Event Monte Carlo (O or EkMC)

Microstructure

Molecular Dynamic (MD)

Atomic Monte Carlo (AkMC)

10 mm

Dislocations and

irradiation defects

Structure

1mm

1 y

1m

1 c

1 mm

10 m

Crystal Plasticity (CP)

Homogenization

Finite Elements (EF)

Cluster Dynamics

TEM

TAP

SANS

Simulation by

charged particles

Experimental reactors MTR SFR

Mechanical tests

GENESIS

March 3-7, 2013

San Antonio, Texas 24

24

GENESIS: International Research Platform

Rouen (open March 2015)

Fundamental / Applied researches, International Platform,

Education

GENESIS – GPM – Rouen Plateform for Nanoanalyses of radioactive materials

And Development of scientific collaboration

Contact : P. Pareige (philippe.pareige@univ-rouen.fr)

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