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PIE-Laser Based Properties Measurements . David Hurley - INL Stephen Reese - INL Farhad Farzbod – INL Marat Khafizov – INL Robert Schley – INL Rory Kennnedy – INL Jianliang Lin – CSM S. Phillpot / A. Chernatynskiy – UF Clarrisa Yablinski - UW Subhash Shinde – SNL - PowerPoint PPT Presentation
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PIE-Laser Based Properties Measurements
David Hurley - INLStephen Reese - INLFarhad Farzbod – INLMarat Khafizov – INLRobert Schley – INLRory Kennnedy – INLJianliang Lin – CSMS. Phillpot / A. Chernatynskiy– UFClarrisa Yablinski - UWSubhash Shinde – SNLHeng Ban - USU
Outline
• Two new laser-based instruments are being designed
• Thermal conductivity microscope
• Mechanical Properties Microscope
• Physics based description of instruments
• Several examples of measurements made on surrogate materials
ATR – NSUF User Week, 2012
• A photon first interacts with the electrons− Electronic and optical properties
• Electronic energy is then converted into heat − Thermal properties
• Thermal expansion (acoustic waves)− Mechanical properties
Motivation• Optical methods are appealing because they can be performed remotely• Optical methods are extremely reproducible • Optical methods have high spatial and temporal resolution
Laser Interaction with Materials
Laser Based Properties Measurements
ATR – NSUF User Week, 2012
Thermal Properties
ATR – NSUF User Week, 2012
Measurement of Thermal Properties – physics description
Phase profile slope = 1/LD
• We have developed a spatially resolved thermal conductivity probe for – investigating individual microstructure features– investigating thin damage layers caused by irradiation
• This approach excites a harmonic thermal wave by a localized pump beam and measures its profile using a localized probe beam
• By combining frequency and spatial domain scan we can extract thermal conductivity (applicable to constant thermal load)
Scan probeThermal wave
ATR – NSUF User Week, 2012
Hurley et al., J. Appl. Phys. 107, 023521 (2001)Khafizov and Hurley, J. Appl. Phys. 110, 083525 (2011)
Example 1 – Thermal anisotropy (atomic bonding)
Phase lag (degrees)
-55
-5
x1
x310 kHz
1 kHz
Phase lag (degrees)
x1
x3
x1
x3
Scan Distance (m)
• Lateral resolution is related to the optical spot size (~1m)
• Depth resolution is related to modulation frequency (1 MHz→100nm)
• Quartz is trigonal and exhibits thermal anisotropy in the plane of the sample
The profile shows conjugate relationship between changes in position and changes in
frequency
Phase contour reveals thermally anisotropic nature of substrate for kilohertz range
modulation
ATR – NSUF User Week, 2012
• Thermal conductivity of UO2 strongly depends on radius• Electrons/phonons/photons are the energy carriers• Thermal conductivity related to ability to transport kinetic energy• In UO2 phonons are primary heat carrier
ATR – NSUF User Week, 2012
Example 2 – The influence of microstructure
Specular
Diffuse
Hot s
ide
Cold side
Nanochannel Boundary
Hot s
ide
Cold side
Internal Grain Boundary
Phonon-phonon scattering
Phonon-defect scattering
Connect microstructure to thermal transport
• Irradiation induced defects that influence thermal conductivity– Fission products– Stoichiometry changes– Dislocation loops– Grains boundaries
• Separate effects studies are important
• High burnup structure at the rim of UO2 fuel pellet exhibits submicron grains with nearly defect free intragrain regions
J. Noirot et al., J. Nucl. Mater. 372, 318 (2008)
• Understand the role of grain boundaries on thermal transport • Two approaches
– Single boundary (Atomistic Simulations)– Many boundaries (Boltzmann Transport Equation)
ATR – NSUF User Week, 2012
Ceria thin film grown on Si substrate using pulsed unbalanced magnetron sputteringGrain size ~ 450 nm
-10 -5 0 5 10-3
-2.5
-2
-1.5
-1
-0.5
0Al/CSM#10: T=300K km=7.36 kf=24.5 ks=156
Distane (m)
phas
e
1 kHz10 kHz100 kHz
KCeO2=7.4 W/mK
• Nanocrystalline thin film has conductivity of 7.4 W/mK much lower than the bulk 15.6 W/mK
• Thermal conductivity in thin film is reduced due to grain boundary scattering
Thermal transport in nanocrystalline ceria thin filmsMetal film is deposited on top of ceria to
ensure strong optical absorption
ATR – NSUF User Week, 2012
Temperature dependent conductivity of ceria samplesParameterize phonon-mean free path
0 50 100 150 200 250 3000
10
20
30
40
50
60
70
80
Temperature (K)
Ther
mal
Con
duct
ivity
(W/m
K)
pelletthin film
• Thermal conductivity of ceria pellet continues to be dominated by ph-ph interactions down to 100 K• Thermal conductivity in thin film is strongly affected by grain boundary scattering to high temperatures
ATR – NSUF User Week, 2012
Grain boundary conductance
• Much lower value than suggested by molecular dynamics modeling in UO2 (0.30 GW/m2K)• For multi-component systems need to include the effect of defect segregation, and stoichiometry
variations near grain boundary
Molecular Dynamics
T. Watanabe et al., J. Nucl. Mater. 375, 388 (2008)
0 50 100 150 200 250 300 3500
20
40
60
80
Temperature (K)
Ther
mal
Con
duct
ivity
(W/m
K)
dTTT 111
0
0 50 100 150 200 250 300 3500
0.01
0.02
0.03
Temperature (K)
GB
Con
duct
ance
(GW
/m2 K
)
ATR – NSUF User Week, 2012
Thermal transport across a single interface
45
-5
-55
-110
nmProfilometry
101100
111
101100
111
HRTEM EELS
4.5 nm O
Si
Fabrication
Interface Characterization
Axes Alignment EBSD
• Original goal: to study transport across Σ29 grain boundary in Si - Silicon has similar optical properties as UO2, the experimental methodology for one material can be
applied to the other- Thermal transport across grain boundaries in silicon has been modeled extensively enabling direct and
immediate comparison of experiment and theory• Interface characterization reveals a 4.5 nm SiO2 layer
D. Hurley, M. Khafizov, J. Appl. Phys. 109,083504 (2011)
ATR – NSUF User Week, 2012
Thermal diffusion across vertical interface
D. Hurley, M. Khafizov, S. Shinde, J. Appl. Phys. 109,083504 (2011)
• Conductance across single Si/SiO2 interface is 0.43 GW/m2K• Conductance across both interfaces and SiO2 layer is 0.11 GW/m2K
ATR – NSUF User Week, 2012
Thermal conductance of interface
• Molecular dynamics simulation using Stillinger Weber interatomic potential
• Transmission of individual longitudinal acoustic phonons (primary source) is modeled
• From calculated transmission coefficients conductance is 0.13 GW/m2K
• Experimentally measured conductance 0.11 GW/m2K
• Overall good agreement between model and experiment– SW potentials generally overestimate
the conductivity
ATR – NSUF User Week, 2012
New Thermal Conductivity Microscope
Lab-based instrument Preliminary design
Mechanical Properties
Laser Ultrasound (brief overview)
Laser generation
Propagation • Elastic and microstructure• Bulk wave velocity – elastic constants
(volumetric)• SAW dispersion - corrosive film thickness
(surface)
Laser detection• Interferometric/holographic • Knife edging
• Electronic and optical properties• For NDE applications in metals typically
thermoelastic• Laser ablation can be used to generate larger
amplitude signal
ATR – NSUF User Week, 2012
Shear
Longitudinal
SAW
Pulse or chopped laser beam
Thermoelastic generation (i.e. nondestructive)
• Far field directivity pattern for bulk shear and longitudinal waves is due to mode conversion at the surface. Very little energy travels along the epicentral direction.
• 70% of energy goes into SAW and 30% into bulk waves• Well defined directivity pattern of shear wave can be exploited for locating flaws
Arrival Time (ns)
Nor
mal
ized
Dis
plac
emen
t
— Experiment— Greens function
Isotropic homogeneous
ATR – NSUF User Week, 2012
Time (ms)
Nor
mal
ized
Am
plitu
de
High temperature elastic properties: Inconel 617Tube Furnace
)21)(1()1(
,
EM
GV
MV sl
ATR – NSUF User Week, 2012
Elastic Constants of Radiological Materials: U-Moly
• RERTR surrogate fuel• Single crystal at RT is orthorhombic – 9 elastic constants• Isotropic if Polycrystalline w/ random orientation• Fuel plate is rolled and may have considerable texture
ATR – NSUF User Week, 2012
Anisotropic Elastic Properties
Grain Boundary
200 µm × 200 µm
Acoustic Wave perspectiveLoad Frame perspective
• Multiple orientations – important waste issues for radiological materials• Nice if we could determine all elastic constants using a single measurement
ATR – NSUF User Week, 2012
Resonant Ultrasound Spectroscopy (RUS)
Inverse problem- Go from spectrum to elastic constants- Turns out that solution is not unique
ATR – NSUF User Week, 2012
In situ changes in microstructure
Using simulation we can predict the relationship between the polycrystalline elastic constants and the evolving microstructure … the appeal of RUS is that it can provide a crucial validation metric for this modeling approach
441211 ,, CCC
Initial Annealed
Temperature (°C)
Freq
uenc
y (k
Hz)
111
101Evolution of microstructure 001
Heat
Polycrystal plasticity model provides the initial dislocation density for the phase field model
A phase field grain growth simulation determines the defect driven grain growth
Averaged elastic constants are measured and computationally determined as a function of time
ATR – NSUF User Week, 2012
Laser RUS in high radiation environment: Gamma tube facility at ATR
In situ laser ultrasonic measurements of Inconel in the high gamma radiation field at ATR showing the sample temperature and resonant frequencies of a split vibration mode as
irradiation was increased by (3 times) placing fuel rods closer to the sample.
Example of moving from the lab to real life
ATR – NSUF User Week, 2012
Mechanical Properties Microscope
Solid Model Rendering Prototype -mockup facility
Thanks!