1
What do we expect from DAFS ? DIFFABS beamline setup Perspectives Simultaneous DAFS and XAFS analyses to evidence the Y- and Ti- species in nano-structured ODS steels Direction de l’Energie Nucléaire Direction déléguée aux Activités Nucléaires de Saclay Département des Matériaux pour le Nucléaire Service de Recherches Métallurgiques Appliquées 10 th SOLEIL USERS’ MEETING – January 22 nd – 23 rd 2015 Denis Menut 1 , Jean-Luc Béchade 1 , Dominique Thiaudière 2 1 CEA, DEN, Service de Recherches Métallurgiques Appliquées, 91191 Gif-sur-Yvette, France 2 Synchrotron SOLEIL, Ligne de lumière DIFFABS, L’Orme des Merisiers, Saint Aubin BP48, 91192 Gif-sur-Yvette, France 4-elementsSilicon DriftDetector Standard XAFS measurementsin fluorescence 1-elem entSiliconDrift Detector Ti Ka and Y Ka-edge DAFS m easurem ents Sam plekeeptin Bragg diffraction condition Vs energy To characterize the microstructure of neutron irradiated materials, various experimental tools are available at the present time in nuclear environment: SEM, TEM, APT, RBS and NRA… However, these techniques are local probes and bring information for an extremely limited sample volume which could be not representative of the whole volume. Therefore, a good statistic can only be obtained by performing many examinations which are very time consuming. Information from other techniques such as APT, TEM and XRD may be useful to help in analyzing the XAFS data. However, the interpretation of XAFS data for industrial material where the absorbing atom studied is located in various secondary phases (showing different compositions, structures, densities, and grain sizes down to few nanometers), even in the matrix, is more challenging than for a quite homogeneous and “pure” material, where target species are clearly located in a specific phase. his issue, Diffraction and Absorption analyses using synchrotron sources are of utmost interest: X-Ray Diffraction (XRD) patterns allow us to identify the precipitates structural changes from line-profile analyses of diffraction peaks, X-ray Absorption Fine Structure (XAFS) spectroscopy is particularly useful for studying, at the atomic scale, the local structure around a specific absorbing atom within the material that possess short-range (up to about 6 Å) or no translational order (amorphous structure). It has enhanced capabilities compared to the separate techniques: DAFS provides EXAFS- and XANES- like information for the specific subset of atoms selected by the diffraction condition. DAFS combines into a single technique: with easuring the elastic Bragg reflection intensities versus photon energy. The long-range order and crystallographic sensitivities of XRD The spectroscopic and short-range order sensitivities of XAFS ODS steel grade : DY Elaborated by mechanical alloying with the nominal composition (in Wt%): Fe-13Cr-1.5Mo-2.2Ti-0.5Y 2 O 3 Material supplied as 9 mm diameter extruded rod. After a 15 min thermal treatment at 1050°C, a final full day treatment was performed at 800°C to induce the -phase precipitation (Fe 36 Cr 12 Mo 3 Ti 7 ) Enhanced mechanical properties due to reinforcement by homogeneous dispersion of nano- sized Y-Ti-O hard particles (~0.2 to 0.6 Wt%) that precipitate from the Fe-Y-Ti-O solid solution during the consolidation Their composition and structures are still not well underst P. Dubuisson et al., ASTM STP 1325 (1999) 882-898 I. MONNET et al., JNM 335 (2004) 311-321 Massive intergranular -phase precipitates Oxides Mean particle radius : ~10 nm (< 25nm) larger oxides ranging 25 – 500 nm Mean particle spacing : ~90 nm 0 50 100 150 200 250 300 350 400 1.98 2.48 2.98 3.48 3.98 Intensity (Sqrt)(a.u.) d-spacing (Å) at4.9 keV at16.9 keV -Fe (110) * * * -phase (120) (111) (120) 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24 0.26 0.017 0.018 0.019 0.020 0.021 0.022 0.023 0.024 0.025 0.026 0.027 4.90 5.00 5.10 5.20 -Fe DAFS ratio (a.u.) -phase DAFS ratio (a.u.) Energy (keV) 0.0000 0.0002 0.0004 0.0006 0.0008 0.0010 0.0012 0.117 0.118 0.119 0.12 0.121 0.122 0.123 0.124 0.125 0.126 0.127 4.9 5 5.1 5.2 XAFS ratio (a.u.) DAFS ratio (a.u.) Energy (a.u.) 0.0015 0.0025 0.0035 0.0045 0.0055 0.0065 0.0075 0.0085 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 16.95 17.15 17.35 17.55 17.75 XAFS ratio (a.u.) DAFS ratio (a.u.) Energy (keV) XRD analyses y = 3.48x 2 -51.65x + 244.07 R²= 1 69 70 71 72 73 74 75 4.85 4.9 4.95 5 5.05 5.1 5.15 5.2 5.25 -phase (120)diffraction lline M axim um intensity position in 2 (°) X-ray energy (keV) Energy Scan from (keV) To energy (keV) Exposure tim e (s) Energy step (eV) 4.9000 4.9640 20 2 4.9645 4.9900 20 0.5 4.9910 5.2000 20 1 Energy Scan from (keV) To energy (keV) Exposure tim e (s) Energy step (eV) 16.950 17.058 30 2 17.060 17.200 30 1 17.202 17.800 30 2 Elastic Bragg intensities Vs photon energy calibration for DAFS at Ti K-edge ( E 0 : 4.964 keV) (the same procedure was used at Y K-edge (E 0 : 17.036 keV) -phase simultaneous XAFS/DAFS analyses Comparison of DAFS analyses at Ti K-edge between the -Fe matrix and -phase precipitates DAFS evidences : That a significant part of Ti atoms are located in the -Fe BCC matrix [S. Liu et al., J. Nucl. Mater. 445, 50-56 (2014); P. He et al., J. Mat. Chem. Phys. 136, 990-998 (2012)]. Both Ti and Y atoms (in a lower proportion) are observed in the intermetallic -phase (1 µm width and 10 µm length with a volume fraction estimated around 17%), thaught to be a quaternary phase of composition Fe 36 Cr 12 Mo 3 Ti 7 [C. Zakine et Al., J. Nucl. Mater. 230, 78-83 (1996)]. However, DAFS measurements on Y-Ti-O nano-oxides were not possible due to their weak and broadened diffraction peaks. Preliminary results Data reduction and analyses under progress 0 2000 4000 6000 8000 10000 12000 14000 68 70 72 74 76 -phase (120)diffraction lline Intensity (a.u.) 2 (°) at4.9 keV at5.0 keV at5.1 keV at5.2 keV (SCK.CEN-Mol; 1975-1980) DY has been neutron irradiated in Phénix as fuel pin claddin

What do we expect from DAFS ? DIFFABS beamline setup Perspectives Simultaneous DAFS and XAFS analyses to evidence the Y- and Ti- species in nano-structured

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Page 1: What do we expect from DAFS ? DIFFABS beamline setup Perspectives Simultaneous DAFS and XAFS analyses to evidence the Y- and Ti- species in nano-structured

What do we expect from DAFS ?

DIFFABS beamline setup

Perspectives

Simultaneous DAFS and XAFS analyses to evidence the Y- and Ti- species in nano-structured ODS steels

Direction de l’Energie NucléaireDirection déléguée aux Activités Nucléaires de SaclayDépartement des Matériaux pour le NucléaireService de Recherches Métallurgiques Appliquées

10th SOLEIL USERS’ MEETING – January 22nd – 23rd 2015

Denis Menut1, Jean-Luc Béchade1, Dominique Thiaudière2

1CEA, DEN, Service de Recherches Métallurgiques Appliquées, 91191 Gif-sur-Yvette, France2Synchrotron SOLEIL, Ligne de lumière DIFFABS, L’Orme des Merisiers, Saint Aubin BP48, 91192 Gif-sur-Yvette, France

4-elements SiliconDrift DetectorStandard XAFS

measurements in fluorescence

1-element Silicon Drift Detector

Ti Ka and Y Ka-edgeDAFS measurements

Sample keept in Bragg diffraction condition Vs

energy

To characterize the microstructure of neutron irradiated materials, various experimental tools are available at the present time in nuclear environment: SEM, TEM, APT, RBS and NRA… However, these techniques are local probes and bring information for an extremely limited sample volume which could be not representative of the whole volume. Therefore, a good statistic can only be obtained by performing many examinations which are very time consuming.

Information from other techniques such as APT, TEM and XRD may be useful to help in analyzing the XAFS data.

However, the interpretation of XAFS data for industrial material where the absorbing atom studied is located in various secondary phases (showing different compositions, structures, densities, and grain sizes down to few nanometers), even in the matrix, is more challenging than for a quite homogeneous and “pure” material, where target species are clearly located in a specific phase.

To address this issue, Diffraction and Absorption analyses using synchrotron sources are of utmost interest: X-Ray Diffraction (XRD) patterns allow us to identify the precipitates structural changes from line-profile analyses of diffraction peaks,X-ray Absorption Fine Structure (XAFS) spectroscopy is particularly useful for studying, at the atomic scale, the local structure around a specific absorbing atom within the material that possess short-range (up to about 6 Å) or no translational order (amorphous structure).

It has enhanced capabilities compared to the separate techniques:DAFS provides EXAFS- and XANES- like information for the specific

subset of atoms selected by the diffraction condition.

DAFS combines into a single technique:

with

by measuring the elastic Bragg reflection intensities versus photon energy.

The long-range order and crystallographic sensitivities of XRD

The spectroscopic and short-range order sensitivities of XAFS

ODS steel grade : DYElaborated by mechanical alloying with the nominal composition (in Wt%):

Fe-13Cr-1.5Mo-2.2Ti-0.5Y2O3

Material supplied as 9 mm diameter extruded rod. After a 15 min thermal treatment at 1050°C, a final full day treatment was performed at 800°C

to induce the -phase precipitation (Fe36Cr12Mo3Ti7)

Enhanced mechanical properties due to reinforcement by homogeneous dispersion of nano-sized Y-Ti-O hard particles (~0.2 to 0.6 Wt%) that precipitate from the Fe-Y-Ti-O solid solution during the consolidation

Their composition and structures are still not well understood

P. Dubuisson et al.,ASTM STP 1325 (1999)

882-898I. MONNET et al., JNM 335

(2004) 311-321

Massiveintergranular

-phaseprecipitates

Oxides

Mean particle radius: ~10 nm (< 25nm) larger oxides ranging 25 – 500 nmMean particle spacing: ~90 nm

0

50

100

150

200

250

300

350

400

1.98 2.48 2.98 3.48 3.98

Inte

nsity

(Sqr

t) (a

.u.)

d-spacing (Å)

at 4.9 keVat 16.9 keV

-Fe(110)

*

* *

-phase(120)

(111)(120)

0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

0.26

0.017

0.018

0.019

0.020

0.021

0.022

0.023

0.024

0.025

0.026

0.027

4.90 5.00 5.10 5.20

-F

e DA

FS ra

tio (a

.u.)

-ph

ase

DAFS

ratio

(a.u

.)

Energy (keV)

0.0000

0.0002

0.0004

0.0006

0.0008

0.0010

0.0012

0.117

0.118

0.119

0.12

0.121

0.122

0.123

0.124

0.125

0.126

0.127

4.9 5 5.1 5.2

XAFS

ratio

(a.u

.)

DAFS

ratio

(a.u

.)

Energy (a.u.)

0.0015

0.0025

0.0035

0.0045

0.0055

0.0065

0.0075

0.0085

0.80

0.85

0.90

0.95

1.00

1.05

1.10

1.15

16.95 17.15 17.35 17.55 17.75

XAFS

ratio

(a.u

.)

DAFS

ratio

(a.u

.)

Energy (keV)

XRD analyses

y = 3.48x2 - 51.65x + 244.07R² = 1

69

70

71

72

73

74

75

4.85 4.9 4.95 5 5.05 5.1 5.15 5.2 5.25

-ph

ase

(120

) diff

racti

on ll

ine

Max

imum

inte

nsity

pos

ition

in 2

(°)

X-ray energy (keV)

Energy Scan from

(keV)

To energy (keV)

Exposure time (s)

Energy step (eV)

4.9000 4.9640 20 2 4.9645 4.9900 20 0.5 4.9910 5.2000 20 1

Energy Scan from

(keV)

To energy (keV)

Exposure time (s)

Energy step (eV)

16.950 17.058 30 2 17.060 17.200 30 1 17.202 17.800 30 2

Elastic Bragg intensities Vs photon energy calibration for DAFSat Ti K-edge ( E0: 4.964 keV)

(the same procedure was used at Y K-edge (E0: 17.036 keV)

-phase simultaneous XAFS/DAFS analyses

Comparison of DAFS analyses at Ti K-edge between the -Fe

matrix and -phase precipitates

DAFS evidences:

That a significant part of Ti atoms are located in the -Fe BCC matrix [S. Liu et al., J. Nucl. Mater. 445, 50-56 (2014); P. He et al., J. Mat. Chem.

Phys. 136, 990-998 (2012)].

Both Ti and Y atoms (in a lower proportion) are observed in the intermetallic -phase(1 µm width and 10 µm length with a volume fraction estimated around 17%), thaught to be a quaternary phase of composition Fe36Cr12Mo3Ti7 [C. Zakine et Al., J. Nucl. Mater. 230, 78-83 (1996)].

However, DAFS measurements on Y-Ti-O nano-oxides were not possible due to their weak and broadened diffraction peaks.

Preliminary resultsData reduction and analyses

under progress

0

2000

4000

6000

8000

10000

12000

14000

68 70 72 74 76

-ph

ase

(120

) diff

racti

on ll

ine

Inte

nsity

(a.u

.)

2 (°)

at 4.9 keV at 5.0 keVat 5.1 keV at 5.2 keV

(SCK.CEN-Mol; 1975-1980)

DY has been neutron irradiated in Phénix as fuel pin claddings