microstructural analysis using x-ray diffraction · microstructural analysis using x-ray...
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11
Microstructural analysis Microstructural analysis using Xusing X--ray diffractionray diffraction
M. LeoniM. LeoniUniversità di Trento – Facoltà di IngegneriaDipartimento di Ingegneria dei Materiali e Tecnologie Industrialivia Mesiano, 77 – 38050 TrentoE-mail: [email protected]
22
Microstructural Analysis using XRDMicrostructural Analysis using XRD
ØØ XX--ray diffraction & materials science/engineering?ray diffraction & materials science/engineering?a case of study: materials for gas turbinesa case of study: materials for gas turbines
ØØ XX--ray diffraction for microstructure analysis: ray diffraction for microstructure analysis: ll what can we measure/obtain?what can we measure/obtain?ll some practical applicationssome practical applications
ØØ Additional topics Additional topics ll the mathematics behindthe mathematics behind……
33
Materials in EngineeringMaterials in EngineeringA case of study: materials for jet propulsion engines
44
Materials in EngineeringMaterials in Engineering
Turbine blades and vanes in different stages
A case of study: materials for jet propulsion engines
55
Materials in EngineeringMaterials in Engineering
Blades and vanes used in different stages of gas turbines must withstand high mechanical and thermal solicitations in hostile atmosphere (corrosion/oxidation)
A case of study: materials for jet propulsion engines
66
High temperature: why?
The quest for high temperature in gas turbinesThe quest for high temperature in gas turbines
• Jumbo-jet engines: 110°C higher Tgas à 20% increase in thrust
• Industrial GTs: 55°C higher gas temp. à 8-13% more power1-4 % higher efficiency
Power and Fuel efficiency are determined by service temperature
77
Turbine blade strengthening phaseTurbine blade strengthening phaseTheThe γγ--γγ’’ microstructure of Nimicrostructure of Ni--based based SuperalloysSuperalloys
γ-γ’ Ni3Al
88
In most metals and alloys, In most metals and alloys, yield stressyield stress ((σσyy) and elastic) and elasticmodulus drastically fall with the temperaturemodulus drastically fall with the temperature
σy(T1)σy(T2)
T1 < T2
yield stress
Yield stress vs. temperatureYield stress vs. temperature
σ
ε
99
Yield stress anomaly in L1Yield stress anomaly in L122 phasesphasesSome NiSome Ni33AlAl--type phases (L1type phases (L122) exhibit a ) exhibit a Yield Stress anomaly Yield Stress anomaly : :
σσyy increases with the temperatureincreases with the temperature
σ y
T
316 - Stainless Steel
Hastalloy - X
Ni3Al
1010
OrderOrder--disorder transformationdisorder transformation
G=HG=H--TSTS
L1L122 (Pm3m)(Pm3m) fccfcc (Fm(Fm--3m)3m)
OrderedLow T
DisorderedHigh T
Al Ni (0.75) Ni - (0.25) Al
Tc
1111
TEM TEM -- SAD in SAD in γγ−−γγ’’
γγ--NiNi33AlAl(disordered)(disordered)
γγ’’--NiNi33AlAl(ordered)(ordered)
1212
γγ--NiNi33AlAl(disordered)(disordered)
γγ’’--NiNi33AlAl(ordered)(ordered)
(200)
(020) (220)
(010)
(100)
(110)
(120)(210)
superstructurereflections
TEM TEM -- SAD in SAD in γγ−−γγ’’
1313
Dislocations in NiDislocations in Ni33AlAl
APDB (APD Boundary)
Ni Al
(111)
Dislocations in Ni3Al superlattice (b=a<101>) are unstable
Partials are separated by two Complex Stacking Faults (CSF) limiting an Anti-Phase Domain (APD) region
APD
CSF CSF(111)
and dissociate in 4 Shockley partials (b=a/6<211>) in the 111 planes.
1414
APBs have a lower energy on 100 than on 111. Thermal activation allows cross slip leading to a non-gliding (sessile) configuration
(010)(111) σ y
T
316 - Stainless Steel
Hastalloy - X
Ni3Al
KearKear--WilsdorfWilsdorf locklock
Kear-Wilsdorf lock
1515
XRD Line Profile Analysis
X-ray diffraction Line Profile Analysis
XRD LPA is ideally suited to determine size/shape of crystalline domains and content of lattice defects (e.g., dislocations, faulting, APDs)
How can we study dislocations, faulting, APBand other features of the microstructure ?
1616
Directional solidification / single crystal
High temperature: why?
The quest for high temperature in gas turbinesThe quest for high temperature in gas turbines
Power and Fuel efficiency are determined by service temperature
1717
High temperature materials in GTHigh temperature materials in GT
Gas turbine achieve high temperatures by air-cooling
Power and Fuel efficiency are determined by service temperature
1818
The quest for high temperature in gas The quest for high temperature in gas turbinesturbines
TBC: Thermal Barrier Coating
Power and Fuel efficiency are determined by service temperature
1919
Thermal Barrier Coatings (Thermal Barrier Coatings (TBCsTBCs))
• TBCs on blades à 107 gals fuel savings per year (250 plane airfleet)
• In aviation engines: à 3x longer life (at 1000-3000 US$ per blade)(data from R.L. Jones, formerly at Naval Research Laboratory, USA)
Blade performance improved by means of ceramic TBCs
2020
TBC Materials: stabilised TBC Materials: stabilised zirconiazirconiaPartially Stabilised-Zirconia (PSZ)(t/t’) or Stabilised Zirconia (c)
Y2O3-ZrO2
2121
PartiallyPartially--stabilised Zirconia TBCstabilised Zirconia TBC
20 30 40 50 60 70 80 90
0
500
1000
1500
2000
2500
3000
3500
M (1
11)
M (-
111)
In
tens
ity (
coun
ts)
2θ (degrees)
27 28 29 30 31 32 33
50
100
150
M (111)M (-111)
Inte
nsity
(co
unts
)2θ (degrees)
Quantitative Phase Analysis (QPA) of Zirconia polymorphsby X-ray Diffraction (XRD) (Rietveld method)
Tetragonal 94.0 wt%Monoclinic 6.0 wt%
2222
Air Plasma Spray (APS)Air Plasma Spray (APS)Plasma Torch
1. Powder injection2. Tubolar anode3. Catode4,6. Cooling system5. Plasma gas inlet
2323
New New TBCsTBCs: APS vs. EB: APS vs. EB--PVDPVDState-of-art: APS (Plasma Spray) New: Electron Beam-PVD
textureno texture
2424
Textured Textured TBCsTBCsMicrostructure of yttria partially stabilised zirconia TBC deposited by EB-PVD: evidence of highly textured columnar grains
Thermal as well as intrinsic (growth) stresses need be considered in coating design and production process
2525
Residual stress and textureResidual stress and textureHow can we evaluate
residual stress and texture in thin films?
X-ray diffraction is ideally suited for non-destructiveevaluation of residuals stress and texture in thin films and coatings.
Structural information must be properly considered in the modelling of the elastic behaviour of textured coatings.
2626
LINE PROFILE ANALYSISLINE PROFILE ANALYSISLPA Applications typically concern the study of:
Ø crystalline domain size and shape (and distribution) Ø generalised line defects, e.g., dislocations, disclinationsØ planar faults, e.g., twin and deformation faultsØ anti-phase domain boundaries (in ordered phases)Ø residual (micro)strain (e.g. by misfitting inclusions)Ø grain surface effects (e.g. grain surface relaxation)Ø impurities (--> lattice parameter fluctuation from grain to
grain)Ø ………..
2727
Starting from the pioneering work of Scherrer (1918), LPA developed during the ’40s and ’50s (Wilson, Warren, Bertaut), with further significant contributions by Krivoglaz and Wilkensduring the ’60s. Profile fitting techniques in the ’80s/’90s had quite an impact on LPA; however, present day traditional LPA methods are still mostly based on those early studies.
Line Profile Analysis: history
• Fourier methods (e.g., Warren-Averbach method)
• Line Breadth ‘simplified’ methods (e.g., Scherrer formula, Williamson-Hall plot)
Traditional methods are usually grouped as:
2828
Line Breadth ‘simplified’ methods
2 0 3 0 4 0 5 0 6 0
2 θ (d e g re e s )
Profile information is typically extracted as FWHM or Integral Breadth (β) – ratio between peak area and maximum intensity
0.0 0.2 0.4 0.6 0.8 1.00.00
0.01
0.02
0.03
slope=2 eintercept=1/KβL
Williamson-Hall plot
β(s)
(Å-1
)
d* (Å-1)
( )* *1 2d e dK Lβ
β = + ⋅
2929
Pattern Decomposition + LPA
2 0 3 0 4 0 5 0 6 02 θ ( d e g r e e s )
2 0 3 0 4 0 5 0 6 02 θ ( d e g r e e s )
Pattern decomposition (profile fitting) is frequently used toextract peak profile parameters by fitting suitable (but arbitrary !!) analytical functions, like, e.g., Voigt, pseudo-Voigt or PVII.
position, width, shape, intensity, asymmetry,…used in LPA (e.g., by Warren-Averbach method)
3030
Most traditional methods are based on a multiple-step procedure:
3. Application of physical models to parameters extracted from theexperimental pattern.
Traditional Line Profile Analysis
20 40 60 80 100 120 1400
1000200030004000500060007000 Sol-gel cerium oxide powder, 1h @ 400°C
Inte
nsity
(co
unts
)
2θ (degrees)
2. Extraction of line profile data (FWHM, β, Fourier coefficients, …),typically by analytical profile fitting
1. Correction of line profiles for the instrumental component/backgr.
( )2cosK Lβ
λβ θ
θ=
⋅
Scherrer formula
3131
Most traditional methods are based on a multiple-step procedure:
1. Correction of line profiles for the instrumental component/backgr.
2. Extraction of line profile data (FWHM, β, Fourier coefficients, …),typically by analytical profile fitting
3. Application of physical models to parameters extracted from theexperimental pattern.
Traditional Line Profile Analysis
Microstructural Parameters
DiffractionPattern
Profile parameters:FWHM, β,
Fourier Coeff. ...Background correction
Peak separation
IP deconvolution
LPA methods:
Scherrer formula
Williamson-Hall,
Warren-Averbach, …
3232
20 40 60 80 100 120 1400
1000200030004000500060007000 Sol-gel cerium oxide powder, 1h @ 400°C
Inte
nsity
(co
unts
)
2θ (degrees)
Microstructural Parameters
DiffractionPattern
WPPMPhysical Model
WPPM is based on a direct modelling of the experimental pattern, based on physical models of the microstructure and lattice defects:
Whole Powder Pattern Modelling
20 40 60 80 100 120 1400
1000200030004000500060007000 Sol-gel cerium oxide powder, 1h @ 400°C
Inte
nsity
(co
unts
)
2θ (degrees)
P.Scardi & M. Leoni, Acta Cryst. A 58 (2002) 190-200
3333
ReferencesReferencesDiffraction Analysis of Materials MicrostructureE.J. Mittemeijer & P. Scardi, editors.Berlin: Springer-Verlag, 2004.
3434
WPPM APPLICATIONSWPPM APPLICATIONS
• Ball milled Fe-Mo powder• Ball milled nickel powder• Nanocrystalline cerium oxide• Cu-Be alloy wear debris• Anti-Phase Domains in Cu3Au
3535
Main sources of broadening in this case are dislocations and domain size. Corresponding fitting parameters are:
WPPM application: Ball milled Fe-Mo
• average dislocation density ρ,
In addition: peak intensities, background coefficients (Chebyshev polynomial), lattice parameter and sample displacement. Data corrected for Lorentz-Polarization effect.
• effective outer cut-off radius Re,
(1 )hkl EDGE SCREWE EC C f C f= + −
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.350.00
0.04
0.08
0.12
0.16
0.20
0.24
0.28
0.32 CEDGE CSCREW
Fe primary slip system: 110<111>Ave
rage
Con
trast
fact
or
H = (h2k2+k2l2+l2h2)/(h2+k2+l2)2
• fraction of Edge/Screw dislocations, fE . Average contrast factor from Feelastic constant, for primary slip system 110<111>:
• mean µ and variance σ of a lognormal distribution of (spherical) domains
3636
WPPM application: Ball milled Fe-Mo
40 60 80 100 120 140
0
500
1000
1500
2000
2500
3000
3500
4000
4500
(2 2 2)(3 1 0)(2 2 0)
(2 1 1)(2 0 0)
(1 1 0)In
tens
ity (c
ount
s)
2θ (degrees)
4 0 6 0 8 0 1 0 0 1 2 0 1 4 0
1 0
1 0 0
1 0 0 0
(2 2 2 )
(3 1 0 )(2 2 0 )
(2 1 1 )(2 0 0 )
(1 1 0 ) F e -1 .5 M o s ta r t in g p o w d e r(d is k 8 0 0 M P a )
Inte
nsity
(cou
nts)
2 θ (d e g re e s )
3737
WPPM application: Ball milled Fe-Mo
40 60 80 100 120 140
0
500
1000
1500
2000
2500
3000
(2 2 2)(3 1 0)(2 2 0)
(2 1 1)(2 0 0)
(1 1 0)In
tens
ity (c
ount
s)
2θ (degrees)
4 0 6 0 8 0 1 0 0 1 2 0 1 4 0
1 0
1 0 0
1 0 0 0
(2 2 2 )
( 3 1 0 )( 2 2 0 )
( 2 1 1 )( 2 0 0 )
(1 1 0 ) F e -1 .5 M o b a ll m il le d 1 0 0 h
Inte
nsity
(cou
nts)
2 θ (d e g re e s )
3838
WPPM application: Ball milled Fe-Mo
0 20 40 60 80 100 120 140 160 1800.00
0.02
0.04
0.06
0.08100h
70h
30h
10h 0h
grai
n di
amet
er d
istri
butio
n (a
.u.)
diameter (nm)
0 20 40 60 80 1000
20
40
60
80
100
120 0h - starting powder (compacted disk)
D α t-0.36
Mea
n cr
ysta
llite
dia
met
er (
nm)
b.m. time (h)
3939
WPPM application: Ball milled Fe-Mo
0 10 20 30 40 50 60 70 80 90 1000.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
b.m. time (h)
Dis
loca
tion
dens
ity, ρ
(x1
016 m
-2)
0
4
8
12
16
20
24
28O
uter cut-off radius (nm)
4040
WPPM application: Ball milled Fe-Mo
0 20 40 60 80 1000.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
b.m. time (h)
Reρ1/
2
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0E
dge fraction, fE
increasing dislocationcorrelation
(1 )Edge Screwhkl hkl hklE EC C f C f= + −
4141
WPPM: ApplicationsWPPM: Applications
• Ball milled Fe-Mo powder• Ball milled nickel powder• Nanocrystalline cerium oxide• Cu-Be alloy wear debris• Anti-Phase Domains in Cu3Au
4242
WPPM Application: Ball-Milled Nickel
40 60 80 100 120 14010
100
1000
10000
Inte
nsity
(co
unts
)
2θ (degrees)
tq h12 h48 h96
Ni patterns at increasing ball milling time
4343
40 60 80 100 120 1400
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
22000
Inte
nsity
(co
unts
)
2θ (degrees)
40 60 80 100 120 140
100
1000
10000 12h ball milling
Inte
nsity
(co
unts
)2θ (degrees)
WPPM Application: Ball-Milled Nickel
4444
40 60 80 100 120 1400
2000
4000
6000
8000
10000
Inte
nsity
(co
unts
)
2θ (degrees)
40 60 80 100 120 140
100
1000
10000
96h ball milling
Inte
nsity
(co
unts
)2θ (degrees)
WPPM Application: Ball-Milled Nickel
NiON
iO
4545
0 20 40 60 80 10002468
10121416182022242628
di
sloc
atio
n de
nsity
, ρo
(x10
15 m
-2)
milling time (hour)0 20 40 60 80 100
51015202530354045505560657075
Mea
n G
rain
dia
met
er (
nm)
milling time (hour)
0 20 40 60 80 1003.5225
3.5230
3.5235
3.5240
3.5245
3.5250
latti
ce p
aram
eter
, ao
(Å)
milling time (hour)0 20 40 60 80 100
0.000
0.005
0.010
0.015
0.020
0.025
0.030
β
α
faul
t pro
babi
lity
α,β
(%
)
milling time (hour)
deformation
twin
WPPM Application: Ball-Milled Nickel
4646
5 nm96h ball milling
WPPM Application: Ball-Milled Nickel
4747
0 20 40 60 80 1000.00
0.04
0.08
0.12
0.16
0.20
0.24
γ
(Jm
-2)
milling time (hour)
2 ln eRD
RAGb
bγ ρ =
RD Dislocations
( )2
ln12 1Disl
Gb D Db
ργ
π ν = −
GB Dislocations
( )
2 ln 216 1Disc
G Dγ
π ν
Ω=
−
Disclinations
WPPM Application: Ball-Milled Nickel
4848
0 20 40 60 800,00
0,02
0,04
0,06
0,08
0,10
0,12 tq h6 h12 h24 h48 h96
grai
n di
amet
er d
istr
ibut
ion
D (nm)
Spherical grain size distributions
WPPM Application: Ball-Milled Nickel
4949
100 nm
Nickel powder ball milled for 96 h
0 10 20 300.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16 TEM WPPM
frequ
ency
D (nm)
WPPM Application: Ball-Milled Nickel
5050
WPPM: ApplicationsWPPM: Applications
• Ball milled Fe-Mo powder• Ball milled nickel powder• Nanocrystalline cerium oxide• Cu-Be alloy wear debris• Anti-Phase Domains in Cu3Au
5151
WPPM: Application - Nanocrystalline Ceria
CeO2 calcinated at 400°C for 1h
Grains are almost spherical and well separated
0 2 4 6 8 10 1205
10152025303540 TEM (average over
800 grains)
Freq
uenc
yGrain diameter (nm)
5252
WPPM Application: nanocrystalline oxidesWPPM Application: nanocrystalline oxidesNanocrystalline cerium oxide from sol-gel route
20 40 60 80 100 120 140
0
1000
2000
3000
4000
5000
6000
7000
Inte
nsit
y (c
ount
s)
2θ (degrees)
• P.Scardi, Z. Kristallogr 217 (2002)• M. Leoni & P.Scardi, in Diffraction Analysis of
Materials Microstructure. E.J. Mittemeijer & P. Scardi, editors. Berlin: Springer-Verlag. 2003
5 nm
5353
WPPM Application: nanocrystalline oxidesWPPM Application: nanocrystalline oxidesNanocrystalline cerium oxide from sol-gel route
20 40 60 80 100 120 140
0
1000
2000
3000
4000
5000
6000
7000
Inte
nsit
y (c
ount
s)
2θ (degrees)
• P.Scardi, Z. Kristallogr 217 (2002)• M. Leoni & P.Scardi, in Diffraction Analysis of
Materials Microstructure. E.J. Mittemeijer & P. Scardi, editors. Berlin: Springer-Verlag. 2003
0 2 4 6 8 10 120
5
10
15
20
25
30
35
40 TEM WPPM
Freq
uenc
y
Grain diameter (nm)
5454
20 40 60 80 100 120 140
0
1000
2000
3000
4000
5000
6000
7000
Inte
nsity
(co
unts
)
2θ (degrees)
1h @400°Cρ≈1.4(9)·1016 m-2
<D> =4.4(6) nm
a0=0.54153(2) nm
WPPM: Application - Nanocrystalline Ceria
> standard value for‘bulk’ ceria (0.54113 nm)
5555
WPPM: Application - Nanocrystalline Ceria
0 2 4 6 8 10 12 14 16 18 200.5410
0.5411
0.5412
0.5413
0.5414
0.5415
0.5416
0.5417
ICDD JCPDS PDF #34-0394 (CeO2)
a 0 (nm
)
Average grain diameter, D (nm)
Refined cell parameters increase with decreasing average grain diameter
300 400 500 6000.5411
0.5412
0.5413
0.5414
0.5415
0.5416
0.5417
a 0 (nm
)
Calcination Temperature (°C)
5656
A core-surface grain modelgrain in polycrystalline sample
Altered corona
Disclinations
grain of powder
Unaltered core
5757
Grain surface relaxation
Yacaman et al., Surf. Sci. 486 (2001) L449-L453
Gold nanorods
5858
A core-surface grain model
2 2 2
R x
adh k lxa ex
κξ−
−
∆∆ =
+ +
∆ =
Shift of atomic layers in the outer corona
a0
a0+∆a
0 1 2 3 40.0
0.2
0.4
0.6
0.8
1.0
∆a (n
m)
position along radius (nm)
5959
WPPM and grain surface relaxationSimulation for CeO2, lognormal distribution of spheres (average 3nm, lognormal
variance 0.3), surface relaxation (A=0.05nm, affected zone B=0.3 nm), dislocations (1016 m-2, Re=3nm), twins (1%) and stacking faults (2%)
40 60 80 100 120 140
1000
2000
3000
4000
5000 W PPM - no GSR W PPM - GS R
Inte
nsit
y (a
.u.)
2θ (degrees)
Main effect of GSR is peak shift (ao changes)
6060
WPPM and grain surface relaxationWPPM GSR-WPPM°
CELL PARAMETERcell parameter (nm) 0.54153(3) 0.541134
SIZE DISTRIBUTION (spherical grains)lognormal µ 1.41(2) 1.42(1)lognormal σ 0.355(7) 0.364(6)average diameter (nm) 4.37(1) 4.40(6)
DISLOCATIONSdislocation density (m-2) 1.4(10) 1016 1.08(4) 1016
edge dislocations content (%) 50 50cutoff radius Re (nm) 2(1) 3(1)A (from elastic constants) 0.1187 0.1187B (from elastic constants) 0.1618 0.1618Wilkens parameter M 0.25(1) 0.31(3)
GRAIN SURFACE RELAXATIONrelaxation factor ξ (nm) 0.008(3)decay constant κ (nm) 0.16(4)
STATISTICAL ESTIMATORSRwp 5.51 5.58Rexp 4.67 4.67GOF 1.18 1.20
fixed !
(°) Rietveld
6161
WPPM and grain surface relaxation
6262
WPPM and grain surface relaxation
6363
WPPM and grain surface relaxation
6464
WPPM - GSR - Rietveld
Structure + Microstructure refinement
20 40 60 80 100 120 140
0
1000
2000
3000
4000
5000
6000
7000
Inte
nsit
y (c
ount
s)
2θ (degrees)
0 2 4 6 8 10 120
5
10
15
20
25
30
35
40 TEM WPPM WPPM - GSR
Rietveld
Freq
uenc
y
Grain diameter (nm)
P.Scardi, Z. Kristallogr 217 (2002)
6565
WPPM: ApplicationsWPPM: Applications
• Ball milled Fe-Mo powder• Ball milled nickel powder• Nanocrystalline cerium oxide• Cu-Be alloy wear debris• Anti-Phase Domains in Cu3Au
6666
WPPM Application: CuWPPM Application: Cu--Be alloyBe alloyApplications: wherever good wear resistance or high mechanical properties are desired coupled with a good electrical or thermal conductivity, such as flash welding dies or parts for electrical components
Pin-on-diskwear test:
Wear debris
6767
WPPM Application: CuWPPM Application: Cu--Be alloyBe alloyFracture tends to become unlikely in small grains (below Griffith critical length) that tend to store high deformation energy. Analogous behaviour is observed in ball milled ceramics. Cu2O has a very low specific dislocation energy (≈1/3 of MgO, 1/30 of Fe3O4), so a high dislocation density is possible. Shear modulus is just G=10.3 GPa à E ∝ Gb2
20 40 60 80 100 120 1400
1000
2000
3000
4000
5000
Inte
nsity
(co
unts
)
2θ (degrees)
WPPMmodelled phases
Cu2O - Pn-3mCu - Fm-3m(CuO - Cc )
0 10 20 30 400.00
0.02
0.04
0.06
0.08
0.10
ρ = 5 x 1016 m-2
Cu2O
dia
met
er d
istri
butio
n (a
.u.)
crystallite diameter (nm)
Wear debris are made of Cu2O (with Cu metal particles).
• Cu2O is stabilised by the very small domain size (<25 nm)
Palkar et al. Phys. Rev. B53 (1996) 2167
• High angle reflections are so broad owing to the very high dislocation density (≈1016 m-2).
0 500 1000 1500-400
-350
-300
-250
-200
-150
-100
-50
0
RT
Cu
Cu2OCuO
2Cu2O + O2
--> 4CuO
4Cu + O2 --> 2Cu2
O
∆G°=RTxln[pO2]
∆G°
[kJ]
Temperature [K]
RT stablephase is
CuO100 nm
6868
WPPM: ApplicationsWPPM: Applications
• Ball milled Fe-Mo powder• Ball milled nickel powder• Nanocrystalline cerium oxide• Cu-Be alloy wear debris• Anti-Phase Domains in Cu3Au
6969
WPPM Application: WPPM Application: APDsAPDs in Cuin Cu33AuAuAnti Phase Domains form during the ordering process in Cu3Au. The o/d process can be thermally activated
7070
(1) (2)
(3) (4)
APB
‘Statistical’Cu(3/4) Au(1/4)Cu
Au
WPPM Application: WPPM Application: APDsAPDs in Cuin Cu33AuAu
7171
WPPM Application: WPPM Application: APDsAPDs in Cuin Cu33AuAu
20 40 60 80 100 120 140
0
200
400
600
800
1000
1200
Cu3Au (traces of Cu
2O)
γ=8% (random + (001))
FFF F
FF
F
F
Inte
nsity
(cou
nts)
2θ (degrees)
[100]
[010]
[001]
20 30 40 50 60
0
50
100
150
200
(211
)
(210
)
(110
)
(100
)
Cu 2O
FF
Inte
nsity
(cou
nts)
2θ (degrees)
7272
Microstructural Parameters
DiffractionPattern
WPPMPhysical Model
Main advantages of the WPPM with respect to traditional methods
WPPM : conclusions
• correct counting statistics is used;
• problem of peak overlapping is intrinsically solved: peak profiles across thewhole pattern are simultaneously refined;
• instrumental profile component can be easily included as well as appropriatebackground functions;
• different line profile models (e.g., dislocation, faulting, APBs, etc.) can betested together (parameter correlations can be evaluated);
• structural constraints can be easily implemented: the WPPM algorithm can hosta Rietveld routine (or vice-versa) for a simultaneous structure-microstructurerefinement
• multiple phase samples can be studied (considering different microstructures)including quantitative phase analysis