ONR DI Present Oct 2011

Galfenol Technologies at

Galfenol Research Initiatives
ETREMA Products

Meeting, Oct. 27, 2011
ETREMA Proprietary Information ‐
State‐of‐the‐Art & Future Direction

Eric Summers, VP & Chief Materials
Engineer
1

• Special thanks to ONR for their support of Galfenol
Research
• Acknowledgements:
• NSWC – Carderock, Magnetic Materials Group including Art Clark

• Ames Laboratory, Dr. Tom Lograsso
• Galfenol MURI members lead by Dr. Alison Flatau
• Kanazawa University, Dr. Toshiyuki Ueno
• All other researchers who have contributed to our body of
knowledge

• Remember: Clark AE, Restorff JB, Wun‐Fogle M, Lograsso
2
TA, Schlagel DL (2000) IEEE Trans Magn 36:3238

Presentation Topics
• Galfenol processing techniques
• Properties
• Future direction of Galfenol

technology
• Galfenol technology roadmap
• Commercialization
3

Magnetostriction vs.
Composition (single crystal)
450
Fe 100‐xGa x
400
H = 15 kOe
Fe1-xGa(0.15 ≤ x ≤ 0.20)
350
3/2 λ100 (x 10 ‐6)

300 • ETREMA’s efforts have

focused on the first
250 magnetostrictive peak between
15 at% Ga and 20 at% Ga
200
• Galfenol alloys available at this
150 compositional range

100 Furnace Cooled
Quenched
50 Directionally Solidified (Unannealed)
Quenched in Brine
Furnace Cooled, Multi‐phase
0
4
0 5 10 15 20 25 30 35 40
x
Single crystal data courtesy of NSWC Carderock Magnetic Materials Group

Galfenol Alloy Feedstock
• Various feedstock alloys and
shapes produced
• Bottom pour unit with 2 kg
capacity – chill cast into
various mold geometries

• Equipment limits capacity
that can be produced

FSZM
Bridgman

Rolling Ingot 5

Primary Production Method

Advanced Bridgman Process
• Directional solidification
method
• Strong <100> texture
• Primary composition = 18.4

at% Ga (nominal)
• Other compositions around 1st
peak can be produced
• Typical geometry: 24 mm dia x
250 mm length
• Current equipment limits rod
sizes that can be produced Photo of Galfenol being produced via Bridgman Process

• Labor intensive 6

As‐Cast Feedstock Alloy
EBSD Comparison
Bridgman Rod

7


Typical Quasi-static Curves

• As‐grown Bridgman rod; Fe – 18.4 at% Ga nominal composition

Strain vs. Magnetic Field Flux Density vs. Magnetic Field 8

Comparison to Terfenol-D
• Less field required to reach • Larger saturation flux density
saturation • Higher permeability
• Larger pre‐stresses necessary • Less hysteresis

Strain vs. Magnetic Field Flux Density vs. Magnetic Field 9

Galfenol Properties
• Typical properties of polycrystalline Galfenol (Fe81.6Ga18.4)
• As‐grown material via Bridgman Process

Saturation Strain 200 – 250 ppm at 48 MPa applied compressive load
Piezomagnetic Constant, d33 15 – 30 nm/A, lower values at larger stresses
Saturating Magnetic Field 100 – 250 Oe, value depends upon stress applied with larger stresses

requiring high magnetic fields to reach saturation

Saturation Magnetic Flux Density 1.5 Tesla
Magnetic Permeability, μr 75 – 100, lower values at larger stresses
Coercivity, Hc 10 Oe
Hysteresis (major loop) 1000 J/m3
Curie Temp. ≈ 950 K
Density 7800 kg/m3
Hard Young’s Modulus 75 GPa
Soft Young’s Modulus ≈ 40 GPa
Tensile Strength ≈ 350 MPa 10
Elongation ≈ 1%

Galfenol Lamination
Benefits Material Permeability Resistivity
• Mechanical robustness (μr) (ρ)
• High permeability Galfenol 75-100 8.5x10-7 Ω·m
• efficient magnetic circuit
Terfenol 2-10 6.0x10-7 Ω·m
• Low magnetic hysteresis

• ~10x less than Terfenol‐D Critical Skin Depth w ith Frequency
100000
Terfenol-D
Galfenol

Disadvantages 10000
Frequency, Hz
• Eddy current losses
• Critical skin depth (20 kHz)
1000
• δGalfenol = 0.38mm (0.015”)
• δTerfenol = 1.23mm (0.048”)
11
• ¼ λsat 100
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Critical Skin Depth, m m

Galfenol Rolling
• Viable high volume, low cost production method
• Highly textured microstructure; (110)<001> ║ RD (Goss)
• Large grains
• Large magnetostrictions measured in individual sheet
samples; > 250 ppm

• Typical sheet dimensions: 11” length x 3” width x 0.014” thick
• Investigating methods to produce thinner sheets
• Lab‐scale process – very labor intensive

12

Rolled Sheet Stacks
• Nominal Ga content: 18
at%
• Multi‐stage rolling to 0.36
mm (0.014”)

• Textured sheets via HT RD

• Sample sectioning RD

• 10 mm x 15 mm ND
TD
• Laminated sheet stack
assembly
• 20 laminates/stack with
~35 µm (0.0015”) bond line 13

d33 = 20 nm/A
λsat = 215 ppm

µr = 85
Msat = 1.3 T
Stack Characterization

14


Galfenol
Machining Examples

15


Welding & Forging

Laser welding courtesy of DRDC Atlantic

16


Stress Annealing at ETREMA
• Stress annealing process builds in a compressive stress into
the Galfenol sample (referred to as an ‘uniaxial anisotropy’)
• Result: full magnetostrictive performance without an extrinsic compressive
stress applied
• Good magnetostrictive performance out into tension

• Maximum built‐in stress achieved = 64 MPa
• Typical = 45 MPa
• Process can be tailored for a certain stress range
• ETREMA has successfully stress annealed Galfenol alloys from
15 at% to 18.4 at% Ga
• Including ternary alloys containing aluminum
• Current equipment limits length of a stress annealed
17
specimen to 125 mm

Test data courtesy NSWC – Carderock Magnetic Materials Group
Galfenol in Tension

18


TECHNOLOGY
FUTURE DIRECTION OF GALFENOL

19


Magnetic Field Annealing
• Magnetic field annealing (FA)
processes under investigation at
ETREMA
• Results consistent with efforts
accomplished under MURI

• Finalizing process parameters
• Currently, small experimental
setup available for field annealing
samples
• 6.35 mm dia x 50 mm length,
typical FA geometry

20
3” x 3” x 6” chamber for FA

Corner Stress Test
Results

21

Test data courtesy NSWC – Carderock Magnetic Materials Group

Strain vs. Magnetic Field
Annealing
Field vs. Stress

Flux Density vs. Magnetic Field

22


Temperature Effects

FA sample, 200°C (not shown)
‐755 hrs exposure, < 5% drop in λsat measured

23

Elevated Temperature
Properties
• Inquiries into designing Galfenol actuators that can operate
under extreme conditions; such as elevated temperature
• Magnetic property characterization at elevated temperatures
• Quasi‐static testing up to 400°C

• λ and B versus H, d33 and μr to be studied

24

Fe-Ga-Al/Fe-Al Alloys
• Reduction in alloy cost critical for
acceptance in commercial
applications
• Today’s Ga market price: $800 ‐
$1000/ kg
• Purchased at significant quantities (50
kg lots)

• Prices trending up
• M.D. Brooks, E. Summers, R. Meloy, J.
Mosley, “Aluminum additions in
polycrystalline iron‐gallium (Galfenol)
alloys,” Proc. SPIE 6929, 69291T
(2008)
• Focus on small diameter, 6.35mm,
FSZM samples
• Fe80.6‐81.6Ga9.8‐13.8Al4.9‐9.8
• Difficulty achieving consistent texture 25
• Scale‐up to Advance Bridgman stage,
evaluate properties

Galfenol Wire Fabrication
• Part of a Phase II SBIR effort on
energy harvesting
• Develop wire fabrication
processing for Galfenol alloys

• ETREMA/Ames Lab
Photos of the 0.014” diameter wire produced of the Fe90Ga10
• Several continuous feet of wire
produced; 10 at% Ga
• Early on in process After drawing

development
• Transition partner identified
and interested in scaling‐up
process if demand exists After HT 26

Galfenol (a non-REE smart technology)
• Supply of Terbium and Dysprosium potentially a problem in the
foreseeable future
• Gallium does not have the same supply risk

27
Figures copied from US Dept. of Energy, “Critical Materials Strategy – December 2010”, p. 8

Galfenol Technology
Roadmap

6.1 (Basic Galfenol Discovery
Research)

6.2 (Advanced Processes Properties
Established Characterized
Research)

6.3 (Technology Actuators
Energy Multifunctional
Harvesters/Sensors Structures
Development)
28

Applications Development
ETREMA
• Significant interest in using Galfenol for energy harvesting
• Medical device tool in early development stage (actuator)
• Very low frequency sources for US Navy

In all cases…costs to produce must be lowered
• Reduce raw material costs
• Scale‐up production

29

Technology
Commercialization
• Current processing technologies nearing a cross‐road
• Alloying, Bridgman, Rolling, Stress Annealing, etc…
• Only capable of producing small quantities
• Process scale‐up absolutely necessary to meet commercial

application quantity and pricing requirements
• Scale‐up will require investment in equipment and
infrastructure ($)
• Difficult to obtain $$$ in today’s low‐risk economic environment
• End‐users must be open to negotiating and executing Supply
Agreements
30

ONR DI Present Oct 2011

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ONR DI Present Oct 2011