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Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Mechanical Properties of High Purity Niobium Novel Measurements
11th Workshop on RF SuperconductivitySeptember 8-12, 2003
G. R. Myneni, S. Agnew, G. Ciovati, P. Kneisel,
W. A. Lanford, R. L. Paul, and R. E. Ricker
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Overview
. Why is an interest in mechanical properties of RRR niobium again?
. What are the Novel Measurements!!
. Where are we going from here?
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
SNS Cavity Field Profile
SNS β =0.61 cavity #3
0
1
2
3
4
5
6
7
8
9
0 5 10 15 2 0 2 5 3 0
Time [ s ]
Before heat treatment After heat treatment at 800C for 6hr.
FPC s id e
Before heat treatmentFrequency = 804.200 MHz
After heat treatmentFrequency = 803.179 MHzFF 26%
Gianluigi Ciovati
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Cavity Tuning Sensitivity
SNS β =0.61 cavity #4 heat treated at 600C for 10 hr - Longitudinal tuning sensitivity
-100
0
100
2 00
3 00
4 00
500
6 00
700
8 00
9 00
0 20 4 0 6 0 80 100 120
C o mp re s s io n [ mils ]
lbs/mils lbs/mils 800C 6hr
Gianluigi Ciovati
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Qo Vs Eacc
061SNS004Q0 vs. Eacc
1.00E+08
1.00E+09
1.00E+10
1.00E+11
0 2 4 6 8 10 12 14 16 18
Eacc [MV/m]
Q0
T=2.17K - Before warm up T=2.17K - After warm up at 120K for 24hrT=2.1K - After heat treatment at 600C for 10hr T=2.1K - After heat treatment and warm up to 120K for 24hr
Design Goal
Gianluigi Ciovati
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Tensile sample
Does not meet ASTM standards but not required since used at very low strain rates
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Tensile apparatus
Unique SystemWide temperature range down to 4.2 KStrain rate variation – six orders
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Measurement Accuracies
. Strain Measurement Accuracy ± 2%
Strain rate can be varied from 1.e-6 s-1 to 10 s-1
. Accuracy of the Stress Measurement ± 1%
. Accuracy of the Percentage of Elongation ± 1%
. Measurements can be made from 4.2 K to ambient temperature
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.0080
20
40
60
80
100
120
as-received 10 hrs at 600oC 6 hrs at 700oC 6 hrs at 800oC
stre
ss (M
Pa)
strain
Apparent YM Issue
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
TD RRR niobium heat treted at 1250 C for 6 hours
0
2
4
6
8
10
12
0 0.002 0.004 0.006 0.008 0.01 0.012 0.014
Strain
Stre
ss (K
SI)
TDA-2-12CTDA-2-27-CTDA-2-35CTDA-2-36CTDA-2-48CTDA-3-60CTDA-4-20CTDA-5-12CTDA-5-41CTDA-5-56CTDA-1-36CTDA-1-139C
RRR=375
TD375 stress-strain
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
TD data summary
Summary of the TD niobium mechanical properties
Niobium Yield Strength (KSI) Tensile Strength (KSI) % Elongation RRR Hv SSR FSR SSR FSR SSR FSR
ASR 7.4 7.9 21 24 44 48 260 52
600 C 7.0 7.5 21 22 48 49 300 47
800 C 5.7 -- 19 -- 47 -- 350 43
1250 C 4.5 6.3 15 19 32 33 375 36
SSR ~ 5.5E-5
FSR ~ 2.0e-4 up to Yield point and 1.0e-3 until break
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
WC Reactor Grade stress-strainEnd Group Reactor Grade Niobium
0
2
4
6
8
10
12
14
16
18
20
0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016
Strain
Stre
ss (K
SI)
RGACCELASR1200Ti6h1250T6hi
RRR=70
RRR=120
RRR=210
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Re la tionship be tween RRR and inte rs titia l impuritie s of Niobium
0
10
20
30
40
50
60
70
80
0 50 100 150 200 250 300 350 400RRR
Inte
rstit
ial i
mpu
ritie
s co
ncen
tratio
n [w
t ppm
ONHC
Interstitials vs RRR
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Ultrasonic Velocity Measurements (University of Va)
. Elastic properties may be accurately measured by the pulse-echo technique. Avoid potential problems of tensile tests (anelasticity, microyielding,
etc.). Assess anisotropy directly by changing the direction of shear wave
polarization (RD,TD)
2155
2244
2333
s
s
l
vC
vC
vC
ρ
ρ
ρ
=
=
=
transducer
pulseecho
pulser
0 2 4 6 8 10 12 14
-4
-3
-2
-1
0
1
2
3
4
2nd reflection
Volta
ge (V
)
Time (µs)
Incident Pulse
Front surface reflection
1st Back-surfacereflection
Delaytime, τ
d
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
. Elastic behavior normal for niobium (E = 110 ± 3 GPa). Anisotropy small (β ≤ 1.03). Reproducible trend with annealing in all lots
20' 600' 700' 750' 800'4000
4400
4800
5200
5600
6000
N P
Velo
city
(m/s
)
Temperature (C)
K
Longitudinal
Shear
20' 600' 700' 750' 800'1800
1900
2000
2100
2200
2300
2400
2500
20' 600' 700' 750' 800' 20' 600' 700' 750' 800'
Velo
city
(m/s
)
Temperature (C)
TD
RD
K
Temperature (C)
TD
RD
N
Temperature (C)
TD
RD
P
450
Velocities (UVa)
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
RRR Niobium Rolled Sheet Textured
. Due to deformation processing and recrystalization
. Anisotropy of single crystal manifest in textured polycrystal. Nb Zener anisotropy parameter, Z = 0.55,
is low (many cubic metals Z>1)
. May predict response of polycrystal response if single crystal behavior and texture are known.. Using averaging schemes such as Voigt, Ruess, Hill
. Initial studies using x-ray diffraction of the sheet surface showed no change in the texture with annealing.
1211
442CC
CZ−
=
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Electron Backscattered Diffraction (EBSD)Utilizes automated indexing diffraction patterns
Provides a method for examining crystallography and crystallographic orientation at a single point in materials
grain boundary crystallography
intragranular substructure (mosaic)
microtexture
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Schematic of EBSD
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Rolling Direction
NormalDirection
100 µm
As-received P sample exhibits bands of fine and coarse grains typical of these samples. Different colors represent orientations as shown in the legend, where the Euler
angles are according to Bunge’s convention
White spots represent positions were surface roughness obscured the EBSD detector
EBSD maps through sheet thickness (UVa)
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
EBSD maps of sheet cross-section provide bulk texture (UVa)
Pole figures from as-received and annealed (800C) samples (lot P) reveal two facts:
Less cube component than in surface (x-ray).
Strengthening of texture with annealing
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
BGO Compton suppressor
Ge gamma detector
Neutron guide (end view)
Lead shielding
Sample
Gamma collimator
γ
γγ
γ
Cold neutron PGAA spectrometer at the NIST Center for Neutron Research
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Schematic drawing for the NIS measurement setup
Cd aperture 9 mm diameter
45°
Neutron beam
Be filter
sample
3He detector
Cd sleeve
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Treatment of niobium samples measuredSample Measured as
received?Measured following:
Measured following:
Measured following:
(No heating) Vacuum heating 1
Acid treatment 1 duration (min)
Vacuum heating 2
Acid treatment 2 duration (min)
Nb 2 No 800 °C / 6 h 1 --- ---
Nb 3 No 700 °C / 6 h 2 --- ---
Nb 4 No 750 °C / 6 h 3 800 °C / 6 h ---
Nb 5 No 600 °C / 10 h 0.5 800 °C / 6 h 5
Nb 6 Yes ---- 4 --- ---
P1 Yes 800 °C / > 48 h ---- ---- ----
P2 Yes 800 °C / > 48 h ---- ---- ----
K1 Yes 800 °C / > 48 h ---- ---- ----
K2 Yes 800 °C / > 48 h ---- ---- ----
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Hydrogen fractions measured in the niobium samplesSample % atom fraction hydrogen
(determined relative blank)
As received After vacuum
heating #1
After acid treatment #1 After vacuum heating #2 (Nb 4) and acid treatment #2 (Nb 5)
PGAA PGAA NIS PGAA NIS
Nb 2 --- 0.138 ±0.025
0.257 ±0.041
0.153 ±0.032
--- ---
Nb 3 --- 0.156 ±0.026
0.169 ±0.028
0.167 ±0.034
--- ---
Nb 4 --- 0.122 ±0.028
0.114 ±0.027
0.083 ±0.020
< 0.03 < 0.03
Nb 5 --- 0.107 ±0.025
0.107 ±0.025
0.113 ±0.024
0.396 ± 0.037 0.352 ±0.070
Nb 6 0.126 ±0.027
--- 0.140 ±0.028
0.150 ±0.032
--- ---
P1 0.03 ± 0.02 < 0.03 --- --- --- ---
P2 0.03 ± 0.02 < 0.03 --- --- --- ---
K1 < 0.04 < 0.03 --- --- --- ---
K2 0.03 ± 0.02 < 0.03 --- --- --- ---
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
NRA Hydrogen depth profilesHydrogen Depth Profile in Niobium
-0.5
0
0.5
1
1.5
2
2.5
3
-0.01 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08
Depth (microns)
H C
once
ntra
tion
(1.e
22/c
m3 )
Vacuum degassed @ 800 C for 6 hHydrogen Charged after vacuum degassingAs received - K TypeAs received - P TypeAs processedVacuum Baked @ 90 C for 48 h
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Hydrogen and Other Interstitials can HaveFour Different Types of Interactions:1. Snoek - Dislocation drag (diffusion)2. Precipitation - Hydrides, etc.3. Pairing Effects - solute-solvent or solute-solute pair
interactions (e.g. Zener effect)4. Gorsky - Large scale diffusion effects
Note diagram shows tensile grip.The measurements of this study were
conducted in 3 point bend.
Dynamic Mechanical Analysis
(Internal Friction)Measures the phase
shift between stress and strain as a function of temperature
Other Peaks:1. Bordoni - Cold work and dislocation
density related2. Grain Boundary - Interface sliding
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Dynamic Mechanical Analysis (Contd.)
Temperature - Relaxation Mechanism KineticsMagnitude - Proportional to Concentration
Peak Temperature = f(Frequency)
Comparison of peaks predicted from diffusion data for two frequencies to measurements.
Peak Magnitude = f(Concentration)
Comparison of the oxygen Snoek peak in two samples of Nb indicated a difference in the oxygen concentration
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Dynamic Mechanical Analysis (Contd.)
Example of other types of interactions and peaks
H-O Interaction Peak
A peak was found at a temperature between that expected for the H and O Snoek peaks. Previous investigators postulated this peak to be due to H-O interstitial interaction.
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Loss Modulus Peaks for NbDynamic Mechanical Analysis (Contd.)
Peak Ratios
Oxygen: P/K ≈ 1.94
Nitrogen: P/K ≈ 1.6
Carbon: P/K NA
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Tensile Deformation andStress Fluctuations During Plastic Flow
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Distribution of Stress FluctuationsDuring Plastic Flow
Standard Deviations
Nb, P = 0.1427 MPaNb, K = 0.0907 MPaRatio P/K = 1.57
Loss Modulus Peak Ratios
Oxygen: P/K ≈ 1.94Nitrogen: P/K ≈ 1.6Carbon: P/K NA
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Analysis of Periodicity of theStress Fluctuations During Plastic Flow
SPD Peak
Nb, P = 2.49Nb, K = 0.56Ratio P/K = 4.44 (2.11)
Standard Deviations
Nb, P = 0.1427 MPaNb, K = 0.0907 MPaRatio P/K = 1.57
Loss Modulus Peak Ratios
Oxygen: P/K ≈ 1.94Nitrogen: P/K ≈ 1.6Carbon: P/K NA
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
2002 Hydrogen in Materials and Vacuum Systems Intl. Workshop
. This International Meeting, the First of its Kind, was Jointly Sponsored by. The Mid-Atlantic Chapter of the American Vacuum Society, . The Old Dominion University (Physics Department),. Deutsches Electronen – Synchrotron (DESY), . The College of William and Mary, . Reference Metals Company Inc., . Tokyo Denkai Co., Ltd. (Japan), . Wah Chang (USA) and. The Jefferson Lab.
. Success Lead to the Formation of International Hydrogen in Matter Symposia Board (ISOHIM): Chair – Dr. Jim Miller, ANL; Co-Chair – Dr. G. MyneniJLAB
. Second International Symposium on Hydrogen in Matter 2005 – Uppsala University, Sweden
. AIP Published the Proceedings of the workshop as CP #671 in July 2003
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
High RRR Nb–Hydrogen Research Collaborations
JLAB – ODU Physics Hydrogen Interactions in Materials – Theory. JLAB – UVa Physics H in Nb Grain Boundaries – SQUID Magnetic
Microscope. JLAB – NIST H–PGAA–Neutron Scattering Studies of high RRR
Niobium. JLAB – NIST Internal Friction Measurements of H and Interstitial
Content in High RRR Niobium. JLAB – SUNY Albany Hydrogen Depth Profile with Nuclear Reactions & Oxide
Thickness in High RRR Niobium. JLAB – DESY, Germany Thermal and Mechanical Properties of Niobium
With Heat Treatments – H Degassing Affects. JLAB – FZK, Germany Extreme High Vacuum Science & Technology – H. JLAB – William & Mary Hydrogen in Semiconductors. JLAB–LANL–UVa – High RRR Niobium Microstructure – Tuning with H
Reference Metals – MOUJLAB – Uppsala Univ. Fundamental Understanding of H-Matter Interactions
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
Conclusions
. High purity niobium mechanical properties vary from batch to batch and are very sensitive to various treatments and handling
. Elastic behavior of high purity niobium is normal and is unaffected by heat treatments
. Hydrogen bulk content and depth profile studies are yielding interesting results
. Internal Friction measurements are expected to provide quantitative interstitial concentrations
. Stress-Strain curves may provide the high RRR Nb purity
. Fundamental hydrogen-matter interactions knowledge from various communities will enhance the understanding and improve the SRF Technology
Thomas Jefferson National Accelerator FacilityInstitute for SRF Science and Technology
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
SRF 2003 3 September ‘03
References. High RRR Niobium Material Studies. Jlab-TN-02-001 Ganapati Myneni and Peter Kneisel
. Requalification of Tokyo Denkai RRR Niobium
. JLAB-TN-02-011 Ganapati Myneni, Peter Kneisel
. Determination of Hydrogen in Niobium by Cold Neutron Prompt Gamma-Ray
. Activation Analysis and Neutron Incoherent Scattering, R. L. Paul, H. H.
. Chen-Mayer, and G. R. Myneni in Hydrogen in Materials and Vacuum
. Systems AIP CP 671, Melville, New York, 2003, pp. 151-161
. Elasto-Plastic Behavior of High RRR Niobium: Effects of Crystallographic
. Texture, Microstructure and Hydrogen Concentration, G.R. Myneni and S.R. Agnew in
. Hydrogen in Materials and Vacuum Systems, AIP CP 671, Melville, New
. York, 2003, pp. 227-242
. Variation of Mechanical Properties of High RRR And Reactor Grade Niobium
. With Heat Treatments, Ganapati Myneni, H. Umezawa in Materiaux & Techniques, Vol
. 7-8, 2003
Ultrasonic Velocity and Texture of High RRR Niobium,. S Agnew, F Zeng, G.R. Myneni in Materiaux & Techniques, Vol 7-8, 2003
. Hydrogen Uptake by High Purity Niobium Studied by Nuclear Analytical
. Methods Rick L. Paul, Heather H. Chen-Mayer, Ganapati Myneni William A. Lanford,
. and Richard E. Ricker in Materiaux & Techniques, Vol 7-8, 2003