C 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
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C
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
- 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
13
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
▲ 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
18
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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C
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
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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,