High Temperature Shape Memory Alloys: From Materials Design to
Device ReliabilityDevice Reliability
Ibrahim KaramanIbrahim KaramanDepartment of Materials Science and EngineeringTexas A&M University, College Station, TX 77843
Graduate Students: A. Evirgen, K.C. Atli, J.A. Monroe, J. Ma, C. Hayrettin, O. Karakoc
Collaborators: D.C. Lagoudas, R. Arroyave, T. Baxevanis, D. Hartl, R.D. Noebe, J. Mabe
How SMAs work?
Courtesy of Dr. Y. Liu
Courtesy of R.D. James
Zn45Au30Cu25
How SMAs work?
Courtesy of Dr. Y. Liu
www.adaptamat.com
SMA‐Enabled Applications and History
Variable Geometry Chevron(2005 Flight Test). Noise reduction and fuel economy
Future Applications, supersonic aircrafts (?)
Variable Area Fan Nozzle(2008) Farnborough
2000 2010 2020• Compact (large energy density)
• large shape change• large actuation force
Reconfigurable Rotor Blade ¼ Scale Wind Tunnel Test
• large actuation force• Lightweight• High Temperature• Relatively inexpensive¼ Scale Wind Tunnel Test
4Ma, Karaman, Noebe, Inter Mater Rev (2010)
Adaptive Trailing Edge(2012 Flight Test)
y p• Reliable
High temperature shape memory alloys: defining transformation temperature above 100 °Ctransformation temperature above 100 °C
Practically: something that works at a higher temperature than NiTiPractically: something that works at a higher temperature than NiTi
Ma, Karaman, Noebe, Inter Mater Rev (2010)
osit
ion,
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e w
ay S
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ility
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es,
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y on
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reve
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n O
Cre
ep oMa, Karaman, Noebe, Inter Mater Rev (2010)
Actuation fatigue is a problem - Not reliable
Ni50Ti50
= 150 MPa Atli, Ph.D. Dissertation, Texas A&M University,2012
• Easy dislocations generation during reversible transformation, poor stability• Thermo-mechanical training is needed to stabilize shape memory response!
NiTiX alloys are less prone to actuation fatigue
Atli, Karaman, Noebe, Mat. Sci. Eng. A, 2013
How can we improve the actuation response of HTSMAs?response of HTSMAs?
• Use conventional metallurgy approaches
– Solid Solution Hardening (quaternary additions)• Atli, Karaman, Noebe et al., Met Trans A 2010, Acta Mat 2011, MSEA 2014.
–Work hardening (thermo‐mechanical processing)• Atli, Kockar, Karaman, et al., Scripta Mat. 2006, J. Nuc. Mat. 2007, Acta Mat. 2010 Acta Mat 2011 Scripta Mat 20112010, Acta Mat. 2011, Scripta Mat. 2011
– Precipitation hardening• Evirgen Karaman Noebe et al Func Mat Letters 2012 Acta Mat 2013Evirgen, Karaman, Noebe, et al., Func. Mat. Letters 2012, Acta Mat. 2013, Scripta Mat. 2013, Acta Mat. 2014, Scripta Mat. 2014, Acta Mat. 2015
–Grain size refinement• Atli, Kockar, Karaman, et al. , Acta Mat. 2010, Acta Mat. 2011, Scripta Mat. 2011a.
T A&M U i it D t t f M h i l E i i
Nano-precipitates in SMAs form hierarchical microstructures
Demonstrated formation of coherent nanoprecipitates in NiTi(Hf,Zr)Texas A&M University Department of Mechanical Engineering
p p ( , )
Ni4Ti3(Ni57Ti43)
Ni-rich NiTi SMA, Ni52Ti4852 48
NiTiHf high Temperature SMAs• The initial
compositions should be Ni-i hrich
• The precipitates
100 m100 nm20 nm 5 nm
precipitates are richer in Ni than the matrix
Ni50Ti50
= 150 MPa = 150 MPa
Ni50.3TiHf20
Under 200 MPa
Significantly improved actuation fatigue response100 Cycles
Aged at 550C, 3 hrs
y
T A&M U i it D t t f M h i l E i i
Nano-precipitates in SMAs form hierarchical microstructures
Texas A&M University Department of Mechanical Engineering
Ni4Ti3(Ni57Ti43)
D i fDesign of nano-precipitates provides new opportunities in SMAs for functional
Ni-rich NiTi SMA, Ni52Ti48
SMAs for functional stability and superelasticity
100 m100 nmNiTiHf high Temperature SMAs FeMnNiAl SMAs
CoNiGa and CoNiAl-based shape memory super alloys
Fine precipitates Large variantsAging at low temperatures or for
Large precipitates Refined variantsAging at high temperatures or for longAging at low temperatures or for
short durations Aging at high temperatures or for long durations
200
150o
550oC
600oC Evirgen, Karaman, et al., Scripta Mat., 2013, Acta Mat. 2014, Scripta Mat. 2014.
100
50
Ms(
o C) 450oC
500oC
FC from 700oC to 100oC
280
240
200550oC
600oC0
100806040200A i Ti (h)
400oCNi50.3Ti29.7Zr20
200
160
120Ms (
o C)
450oC
500oCAging Time (h)
80
40
0302520151050
Ni50.1Ti24.9Hf25
• Great flexibility to modify transformation temperatures (same trend in Af), and hysteresis (dissipative mechanisms)
302520151050Aging Time (h)
600
580
560(ºC
)
160 150
140 130 120
110
110
100
80
90
Region 1
Af
Nanoprecipitates540
520
500
empe
ratu
re 0 110 100
80
70 6
0
8070
80
5090 suppress functional
degradation480
460
Te
1 10 100 1000
80
Region 2 60
50
5
40 600
580 100 90
80
80 30
20
70Ms
degradation
Time (min)560
540
520ratu
re (º
C) 80
60 40
30
2
10
Region 1
2
70
50
New NiTiHf and 520
500
480
460
Tem
per 30
10
0
0
-20
-40 Region 2 -30
-10
-10-20
1020
NiTiZr alloys are less prone to actuation
Evirgen, Karaman, Noebe, Acta Materialia, 2015
460
1 10 100 1000Time (min)
0 10prone to actuation fatigue
Work Output of Comparison
103
104
Elect rost rict ive ceramics
Magnet ic SMAs (MSMAs) (Field induced phase t ransformat ion) TWSME in
Ni Ti Hf
102
10
ss (M
Pa)
Magnet ost rict ive mat erials
Shape memory alloys (SMAs)
100
Ni50.3Ti29.7Hf20
101
tion
Stre
s
TWSMEin SMAs
Piezolect ric ceramics
El t t i
10 MJ/ m 3
00 MJ/ m 3 TWSME inNi24.5Ti50.5Pd25
TWSME inNi49 9Ti50 1
10-1
100
Act
uat
Piezolect ric polymers
MSMAs (Field induced variant
Elect roact ive polymers
Shape memory polymers
1 MJ/ m 3
Ni49.9Ti50.1
10-2
0.01 0.1 1 10 100 1000
p y ( reorient at ion)
10 J/ m 3
100 J/ m 31 kJ/ m 3
10 kJ/ m 3
100 kJ/ m 3
Actuation Strain (%)
Atli, Karaman, Noebe, Smart Materials and Structures, 2015
Microstructure generation• Multiple RVEs of SMA matrix and
elastic Ni4Ti3 precipitates
Micromechanics• Periodic boundary conditions
for stress, strain, and Ni-t ti
Coherency stress field• Mismatch between the lattice
parameters of the two phasesconcentration
Ni-depletion (3D Fick’s law)• Representative of precipitate
formation
Thermo-mechanical response prediction Thermal cycle microstructure and obtain response
AppliedLoad
2
3
4
5
6
Strain [%
]
150 MPa
ExperimentPrediction
Ni-content distributionTypical stress field under macroscopic load
‐1
0
1
‐50 ‐25 0 25 50 75 100 125 150
Temp [°C]
Current work• Given solutionized material response and calorimetric data after heat treatment,
Predict precipitated material response
Precipitation RelationsSolutionized Material Response
Response Prediction600
580 160
150 141
110
10
90
Af
2
3
4
5
6
rain [%
]
Experiment
Calibration
580
560
540
520
500mpe
ratu
re (
ºC) 140 130
120
0
110
00
100 80
70 6
0
8070
80
Region 1
0
90
Af
‐1
0
1
‐50 ‐25 0 25 50 75 100 125 150
Str
Temp [C]
480
460
Tem
1 10 100 1000Time (min)
80
70
Region 2 60
50
50
40
0123456
Strain [%
]
‐10
‐50 ‐25 0 25 50 75 100 125 150Temp [°C]
What is next?What is next?• Design of HTSMAs with operating temperatures between 500°C to 800°C – Discovered a new class of materials that works around 600°C
• Better understanding of fatigue and fracture g gmechanisms in HTSMAs
• Accelerated Alloy and Processing DesignAccelerated Alloy and Processing Design• Ultra‐high temperature shape memory ceramics
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