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Invited lecture of the Simposium N "Surface Engineering - functional coatings and modified surfaces" at the XIII SBPMat (Brazilian MRS) meeting, in João Pessoa (Brazil). The lecture took place on September 30th, 2014. The speaker was Professor Christoph Genzel, from the Helmholtz-Zentrum Berlin für Materialien und Energie (HZB), in Germany, where he heads the Department of Microstructure and Residual Stress Analysis and he coordinates a group of diffraction and scattering. Genzel is also Associate Professor at the Technische Universität Berlin.
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XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Thin films seen in the light of high energy synchro-tron radiation: Stress and microstructure analysis using energy-dispersive diffraction Dept. of Microstructure and
Residual Stress Analysis
Ch. Genzel
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Outline
BESSY II Introduction Angle- vs. energy-dispersive
diffraction Basic principles of X-ray stress
analysis (XSA)
Examples XSA on coated cutting tools Stress and composition gradients In-situ study of thin film processing What about the microstructure?
Summary
2
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 20143
The Mission of the Helmholtz-Zentrum Berlin
WannseeBER II Reactor
AdlershofBESSY II
Two large scale facilities for investigating the structure and function of matterEnergy research
SynchrotronNeutrons
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 20144
Department of microstructure and residual stress analysis
Synchrotron
ASAXS
Diffraction:Stress, texture, microstructure
Scattering:Nanostructure
Imaging:
E3
Neutrons
Synchrotron
EDDI
Time resolution
Depth resolution
Spatial resolution
X-ray
ETA
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Thin films and coatings in every day use
CISCIS
Thin films and coatings fulfill various important functions in our daily life …
5
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Designing of property-enhanced coating systems
Composition &Microstructure Texture
Residual stress
Al2O3
TiCN
Coating properties can be tailored in the manufacturing process.
6
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
The role of diffraction methods ...
7
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Information provided by X-ray diffraction
Energy [keV]
Inte
nsity
[a. u
.]
afterbefore sulphurization
X-Ray Diffraction: Crystal structureNondestructivePhase-selectiveInformation depth nm ... cm
Line width and shape: Domain/particle size Microstrain, lattice defects
Line intensity: crystallographic texture Reaction kinetics
Fluorescence lines: Element distribution
Line position and shift: Crystal structure Residual stresses
8
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 20149
Challenges in structural research with diffraction methods
9
Investigations should be done ...
... in situ (time resolution)
0 5 mint ... with high spatial resolution
zxy
... under service conditions
sload
RT
1000 ºC
T
Thin films: Superposition of gradients of residual stress, texture and composition on very limited space!
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Well-known and mainly used: Angle-dispersive X-ray diffraction
0D: Scintillation counter 1D: Position sensitive det. 2D: Channel plate
2q
Photon source
monochromatic X-ray beam
2q [deg]
30 40 50 60 70 80 90
0
5
10
15
I [cp
s]
CoKa surface sensitive (low energies) high angular resolution long counting times (scintillation
counter) complex experimental setup
variable!substrate
coating
10
E1 = E2 = E3 …
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Features of energy-dispersive X-ray diffraction
fixed!
white beam
substrate
Fixed experimental setup Complete diffraction patterns
in fixed directions (unique!) Different diffraction lines Ehkl
originate from different depths
coating
E1 < E2 < E3 …
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XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 201412
Strategy for coating stress analysis
Materials Science Beamline EDDI
ETA diffractometer
Angle-dispersive diffraction (lab) Low energies (5 … 17 keV) Surface sensitive
coating
substrate
Energy-dispersive diffraction (synchrotron) Energies up to 120 keV Sensitive in deeper zones
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
The EDDI beamline for Energy Dispersive DIffraction
EDDI@BESSY II: E (8 … 120) keV 2.4·1011 ph·s-1/0.1% bw
Experimental hutch
PVD chamber Two detector setup
DHS 1100 heating station Mechanical load device
High resolution setup
13
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Basic principles of X-ray stress analysis
14
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Principle of residual stress analysis by diffraction methods
angle-/energy-dispersive
15
1. Measurement of the diffraction line shift for various orientations ( ,j y)
2. Evaluation of the lattice strain
3. Evaluation of the residual stress tensor via Hooke‘s law.
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
The sin2 -y method
0 1
In-plane homogeneous film with biaxial residual stress state:
Fundamental equation of X-ray stress analysis takes the form:
Residual stress (s z) require a more sophisticated treatment ...
m > 0: tensile stress
m < 0: compressive stress
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XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
XSA on coated cutting tools
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XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 201418
XSA on multilayer systems: Influence of the coating design
5µmWC
TiCNAl2O3
WCTiCN
Al2O3
10µm
„Thin“system (D = 5 µm) „Thick“system (D = 18 µm)
TiCN
0.2 0.4 0.6 0.8 1 0.0873
0.0875
0.0877
0
d42
2[n
m]
sin²
blasted
as-grown
0.2 0.4 0.6 0.8 1 0.0873
0.0875
0.0877
0
d42
2[n
m]
sin²
blasted
as-grown
0.2 0.4 0.6 0.8 1
0.08750
0.08755
0.08760
0
d422
[nm
]
sin²
blasted
as-grown
0.2 0.4 0.6 0.8 1
0.08750
0.08755
0.08760
0
d422
[nm
]
sin²
blasted
as-grown
CuKa
Al2O
3
0.2 0.4 0.6 0.8 1
0.172
0.174
0.176
0
d024
[nm
]
sin²
blasted
as-grown
0.2 0.4 0.6 0.8 1
0.172
0.174
0.176
0
d024
[nm
]
sin²
blasted
as-grown
0.2 0.4 0.6 0.8 1
0.1715
0.1725
0.1735
0.1745
0
d024
[nm
]
sin²
blasted
as-grown
0.2 0.4 0.6 0.8 1
0.1715
0.1725
0.1735
0.1745
0
d024
[nm
]
sin²
blasted
as-grown
CuKasteep stress gradient!
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
ED-XSA in the interfacial substrate zone
30 40 50 60
200
400
600
800
1000
E [keV]
I [ct
s]
001-
WC
101-
WC
110-
WC
002-
WC
111-
WC
100-
WC
coating reflections
30 40 50 60
200
400
600
800
1000
E [keV]
I [ct
s]
001-
WC
101-
WC
110-
WC
002-
WC
111-
WC
100-
WC
coating reflections
2q = 9°2q = 9°
5µmWC
TiCN
Al2O3
E1 < E2 < E3
M. Klaus et al., Thin solid films 517 (2008), 1172.
1 2 3 4 5 6 7
-1.5
-1.0
- 0.5
0
001
111
002
110
101
001
0
||[G
Pa]
[µm]
blasted
as-grown
1 2 3 4 5 6 7
-1.5
-1.0
- 0.5
0
001
111
002
110
101
001
0
||[G
Pa]
[µm]
blasted
as-grown
coating
19
Application of the sin2y-method to each line Ehkl
Assignment of the obtained stress values <shkl> to average information depth <thkl>
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
5µmWC
TiCNAl2O3
z [µm]
4 8 12 16 20
- 6
- 4
- 2
0
2
0
- 8
||
[GP
a] TiCN
TiN
Al O 3
BL
as-grown
blasted
2
WCTiCN
Al2O3
10µm
z [µm]
1 2 3 4 5
- 6
- 4
- 2
0
2
0
- 8
||
[GP
a]
TiCN
TiN
Al O B
L
as-grown
blasted
2 3
1 2 3 4 5 6 7
-1.5
-1.0
- 0.5
0
001
111
002
110
101
001
0
||[G
Pa]
[µm]
blasted
as-grown
1 2 3 4 5 6 7
-1.5
-1.0
- 0.5
0
001
111
002
110
101
001
0
||[G
Pa]
[µm]
blasted
as-grown
1 2 3 5 6 7
-1.5
-1.0
-0.5
0
111
002
110
101
001
0 4
||[M
Pa]
[µm]
blasted
unblasted
1 2 3 5 6 7
-1.5
-1.0
-0.5
0
111
002
110
101
001
0 4
||[M
Pa]
[µm]
blasted
unblasted
Interlayer gradient: Balance between coating and substrate
Intralayer gradient: Balance within the Al2O3 top layer
Residual stress balance in multilayer systems
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XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014 21
Separation of residual stress and composition gradients
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 201422
Residual stress analysis in expanded austenite layers
2q = 8°
111-N
111
200-N 200
Substrate
Exp. austenite
S. Jegou et al. Thin solid films 530 (2013), 71.
Residual stress (-N) Composition (-N) Strain depth profiling
in the scattering vec-tor mode.
Application of the sin² method for predefined depths .
t = 5 µmm
sin2y*
d0
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Energy-dispersive diffraction:In-situ study of thin film processing
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XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 201424
Rapid thermal processing (RTP) of CuInS2 thin films
Sulphurization of Cu/In precursor on Mo/glass substrate
Sulphurization chamber mounted on the diffractometer.
Fast recording of ED spectra
Indium
CopperMolybdenium
Glass
metallic precursor
CuInS2
Sulfur
DE
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
The two-detector setup @ EDDI
Simultaneous acquisition of diffraction patterns in fixed but arbitrary measuring directions!
High resolution In-situ
sin²y
dy
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XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
In-situ analysis of thermal stresses in thin Mo films on glass
Ch. Genzel et al., J. Strain Analysis 46 (2011), 615
Mo = 510-6 K-1 / Glass = 9.510-6 K-1
sin2y-based stress analysis
Ds
26
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
What can we learn about the microstructure?
27
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014 28
In-situ microstructure analysis: recrystallization of CuInS2
10 50 100 150 Process time [min]
Ene
rgy
[keV
]
30
Substrate temperature [ºC]50 150 250 350 450
Recrystal-lization
H. Rodriguez-Alvarez, PhD thesis, TU Berlin, 2010.
112- CuInS2
Small-grained, defective CuInS2
Recrystallized CuInS2
Driving Forces?Enhancement?
112- CuInS2
29 30 31 32 33Energy [keV]
Lorentzian, broad
Nor
mal
ized
Int
ensi
ty [
a. u
.]
Gaussian, small
Energy-dispersive diffraction line profile analysis?
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Instrumental resolution in ED diffraction (EDDI beamline)
Instrumental resolution:
( G – Full width at half maximum)
LaB6 SRM660b Energy-dispersive RIETVELD refinement:
D. Apel et al., Z. Kristallogr. 226 (2011), 943.
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XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Multiple vs. single line analysis
2 = 10°CeO2 ED Rietveld study of size-related
broadening in ceria powder: EDDI: DV = 226(31) Å+)
Size-Strain RR: DV = 221…236 Å++)
+) D. Apel et al., Z. Kristallogr. 226 (2011), 943.++) D. Balzar et al., JAC 37 (2004), 911.
112- CuInS2
29 30 31 32 33Energy [keV]
Nor
mal
ized
Int
ensi
ty [
a. u
.]
Energy [keV]
Inte
nsity
[co
unts
x 1
03 ] Needs single line analysis!
30
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Single line analysis of domain size and microstrain
D. Thomas, PhD thesis, TU Berlin, 2012.
Broadening angle dispersive energy dispersive
Size
Strain
Size and strain broa-dening depend on q!
Only strain broade-ning depends on E!
Line profiles described by pseudo-Voigt (pV) functions:
pV(E) = x·Cauchy(E) + (1-x)·Gaussian(E) (0 x 1) Domain size Cauchy width bC
Micro strain Gaussian width bG
dom
ain
size
[nm
]
interrupt temperature [°C]
mic
ro s
trai
n [%
]
initial state
31
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Summary
Energy-dispersive synchrotron X-ray diffraction: Versatile tool for many fields of materials sciences.
Under fixed diffraction conditions complete diffrac-tion patterns are recorded.
Thin film analysis and (high energy) ED diffraction fit together! The methods allows for:o (Residual) stress analysis, even in complex cases (multi-
layers, separation of stress and composition gradients ...)o Fast in-situ study of thin film growth processeso Microstructural characterization (ED line profile analysis)o ...
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XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
My special thanks go to:Manuela KlausIngwer A. DenksRodrigo CoelhoDaniel ApelDiana ThomasMatthias MeixnerTillman FussGuido Wagener
Roland MainzHumberto Rodriguez-Alvarez
Davor Balzar
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XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Thank you very much for your attention!
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