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European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
New 3-D Bulk ShapedPolycrystalline and Nanocomposite
Magnetostrictive Materials*
N. Lupu #, H. ChiriacG. Ababei, M. GrigorasM. Valeanu
T. Buruiana,V. HarabagiuI. Mihalca
*This work was generated in the context of the MESEMA project (http://www.mesema.info), funded under the 6th Framework Programme of the European Community (Contract N° AST3-CT-2003-502915) and MAGSAT project (Contract No 34/2005) (http://www.phys-iasi.ro/ift/MAGSAT.htm) funded under CEEX Programme of the Romanian Ministry of Education and Research – National Authority for Scientific Research.#Address for correspondence: [email protected]
National Institute of R&D for Technical Physics, Iasi, RomaniaNational Institute of Materials Physics, Bucharest-Magurele, Romania“Petru Poni” Institute of Macromolecular Chemistry, Iasi, RomaniaCondensed Matter Research Institute, Timisoara, Romania
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
� Magnetostriction
OutlinesOutlines� Magnetic Sensors and Actuators vs. Smart Materials� Fe-(Ga,Al) magnetostrictive alloys� (Co,Ni)-Mn-(Ga,Al) magnetostrictive alloys� (Fe,Co)-RE-B magnetostrictive materials (RE = Tb, Dy, Sm)� Conclusions & Potential Applications
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
Magnetostrictive materials are changing their shape due to the change in the magnetization state of the material.
Although nearly all ferromagnetic materials exhibit a shape change resulting from magnetization change, only those with significant interactions between shape change and magnetization change are suitable for sensors/actuators applications.
Magnetostriction (1)Magnetostriction (1)
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
� Magnetostriction - a consequence of the magnetoelastic coupling.� Magnetostriction is an intrinsic property of magnetic materials, which
is for a crystalline material a direction dependent tensor λhkl mainly caused
by the orbital coupling of the magnetic moment.� Linear, , or volume magnetostriction .� Positive when the material is elongated and negative when is
contracted.
Magnetostriction (2)Magnetostriction (2)
llδ VVδ
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
� Saturation magnetostriction (λs) - the magnetostrictive deformation of a
material increases with the applied magnetic field increase and reaches the
maximum value.� Isotropic magnetostriction = spontaneous deformation “e” is constant
in all crystallographic directions.� Anisotropic magnetostriction = the sign and value of deformation
depend on the crystallographic direction.
Magnetostriction (3)Magnetostriction (3)
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
Magnetostriction Magnetostriction –– How to measure it (1)How to measure it (1)� The magnetostriction can be measured by direct and indirect methods.� Direct methods: with strain gauges, capacitance transducers or interferometers.� For crystalline materials the use of strain gauges is most common.� The most sensitive method is the capacitance method.� Disadvantages of direct methods: they require a special sample preparation and they do not deliver the “true” saturation magnetostriction.� Indirect methods: Becker-Kersten method and SAMR method (Small Angle Magnetization Rotation).� Becker-Kersten method - the magnetostriction is determined from the
stress dependence of the hysteresis loop.� SAMR - for soft magnetic ribbons/wires because of the special geometry. Beside the stress dependence of the hysteresis the SAMR method delivers very accurate results. This method can also be used from 4.2 K up to high temperatures.
C. Polak, Thesis, TU Wien, 1992.
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
Comparison of some methods to measure magnetostrict ion
Variation of SAMR method~ ±10-9IndirectTransverse susceptibility
High sensitivity, suitable for ribbons,
usable at all temperature to determine λs
~ ±10-9IndirectSAMR(Small AngleMagnetisationRotation)
Good for negative and very small value
of λs
~ ±10-8IndirectStressdependence ofhysteresis loop
Most sensitive method but also difficult
to carry out at high temperature
~ ±10-10DirectCapacitance
Determine λ// and λ┴ independently,
difficult to perform at high temperature
±1 x 10-6DirectStrain gauges
RemarksSensitivityMannerMethod
Magnetostriction Magnetostriction –– How to measure it (2)How to measure it (2)
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
� Both magnetic sensor and actuator materials require strong interaction between the magnetic response and other responses to external factors (resistance, stress, strain, etc.).� Actuators materials are generally “hard” materials since significant stress is required for actuators to work.� Magnetic sensors materials can be “soft” materials, BUT high sensitivity and low noise level are important.� There is no clear “border” between magnetic sensors and actuators materials, and some actuator materials can be used as sensor materials as well.
Magnetic Sensors and Actuators vs. Smart Materials (1)Magnetic Sensors and Actuators vs. Smart Materials (1)
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
Magnetic Sensors and Actuators vs. Smart MaterialsMagnetic Sensors and Actuators vs. Smart Materials
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
Properties of Different Smart MaterialsProperties of Different Smart Materials
N/AMedium10-1004ElectroactivepolymerP(VDF-TrFE) N/AFast> 10000.12PiezoelectricPZT N/ASlow10-20> 5Shape Memory Alloy (SMA)Ni-Ti(Nitinol) ~380Fast> 505Ferromagnetic Shape Memory Alloy (FSMA)Ni-Mn-Ga ~923Fast< 150.013-0.025MagnetostrictorFe-Ga(Galfenol) 660Fast< 150.14-0.2MagnetostrictorKelvinAll®(EMERGEN) 653Fast< 150.16-0.24MagnetostrictorTb0.3Dy0.7Fe1.9(Terfenol-D) Curie Temperature (K)Relative Response SpeedActuation Voltage (V)Maximum Strain (%)Material TypeMaterial
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
� The fabrication of highly efficient integrated magnetostrictive sensors,
actuators and transducers requires the availability of magnetoelastic
materials with high magnetostriction and low saturation fields in different
shapes, depending on the final application.� Terfenol-D is the most used magnetostrictive material for
magnetostrictive actuators and transducers;� magnetostrictive metallic glasses are preferred for sensors applications;
Magnetic Sensors and Actuators vs. Smart MaterialsMagnetic Sensors and Actuators vs. Smart Materials
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
Magnetostrictive Materials Magnetostrictive Materials –– TERFENOL AlloysTERFENOL Alloys
The highest room temperature magnetostriction of a pure element is Co, which saturates at 60 ppm.
TERFENOL-D: Courtesy of ETREMA Inc.
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
Magnetostrictive Materials Magnetostrictive Materials -- METGLASMETGLAS
METGLAS (Fe-based alloy), discovered in early 1980s, is a good sensor material with an amorphous structure.
Why amorphous? The amorphous structure of METGLAS makes it have a smaller anisotropy energy compared with magnetocrystalline materials.
Annealing METGLAS in a magnetic field produces a well-defined anisotropy direction but with the smallest possible magnitude of anisotropy energy.
Magnetic moments rotate, without any domain wall motion.
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
D = dλ/dH - the rate at which the strain is developed with respect to the applied field.
H. Chiriac et al., Sensors and Actuators 81 (2000) 166.
Ferromagnetic METGLAS can effectively increase magnetostriction than crystalline materials, at the same magnetic field level.
Magnetostrictive Materials Magnetostrictive Materials -- METGLASMETGLAS
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
TERFENOL
1. Cubic C15 structure
2. Large magnetostrictive strains of the order of 0.1 % at and above RT
3. Brittle, large field for saturation,
expensive Tb and Dy
METGLAS
1. Amorphous
2. Low saturation magnetostriction
(30 x 10-6 for Fe81B13.5Si3.5C2)
3. Low field for saturation, large magnetomechanical coupling coefficient
New materials to combine the advantages of both materials.
Magnetostrictive MaterialsMagnetostrictive Materials
Very recently, 2 new alternatives appeared:� Fe-(Ga,Al) alloys, as single crystals and melt-spun ribbons� Ni-Mn-Al and Co-based magnetic shape memory alloys (MSMs)
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
Fe-(Ga,Al) system
(Galfenol Alloys)
“GALFENOL is the latest magnetostrictive material to be invented, and is currently under development. Originally invented in 1998 by the Magnetic Materials Group at NSWC-CD, GALFENOL is slowly emerging into the real world. While its magnetostriction is only 1/3rd to 1/4th that of Terfenol-D, GALFENOL is a much more robust material allowing it to be used in harsh mechanically harsh environments with minimal shock hardening.” (ETREMA Products, Inc. website)
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
3D3D--Bulk Shaped Samples PreparationBulk Shaped Samples Preparation
Magnetostriction measured by the electrical resistance strain gauge technique.
3-D shaped Fe100-x(Ga,Al)x polycrystalline magnetostrictive alloys (x = 13÷30) as thin plates of 12*6*0.5 mm and 40*5*1 mm, rods (6 mmφ and 40 mm long) and bars 3*3*10 mm3.
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
MeltMelt --Spun Ribbons PreparationSpun Ribbons Preparation� Ribbon samples were produced by melting 3 grams of ingot with an induction coil in a partial argon atmosphere and ejecting the melt onto a rotating copper wheel at a wheel speed of 35 m/s.� Isothermal heat treatment was performed on some ribbon samples at 10000C for 72 hours and then:� slow quenched to RT, OR� slow quenched to 8000C, then water
quenched.� Ribbons were evacuated in a quartz tube and then sealed with approximately one atmosphere of argon at the annealing temperature.
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
StructureStructure
The XRD patterns of as-quenched melt-spun ribbons and bulk shaped samples don‘t show any texture.
In addition, to the primary reflection at ~ 440 (110) and ~ 640 (200), none reflections corresponding to the DO3 phase are observed.
Fe-Ga19.5Fe-Ga22.5
Lin
(Cou
nts)
0
10 0
20 0
30 0
40 0
50 0
60 0
70 0
80 0
90 0
10 00
11 00
12 00
13 00
14 00
15 00
2-Th eta - S cale
3 1 40 50 6 0 70 8 0
FeFe-Ga17.5
Melt-spun ribbonsFe-Ga15
Lin
(Cou
nts
)
0
10
20
30
40
50
60
70
80
90
10 0
11 0
12 0
13 0
14 0
15 0
16 0
17 0
18 0
19 0
20 0
21 0
22 0
23 0
24 0
25 0
26 0
27 0
28 0
2-T h eta - S ca le
31 40 50 60 70 8 0
FeFe-Ga19.5
Cast bars 3 x 3 x 10 mm3Fe-Ga17.5
Investigated using both the conventional X-ray diffractometer and the high energy X-rays synchrotron radiation (ID11 @ ESRF Grenoble)
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
-0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8-200
-150
-100
-50
0
50
100
150
200
As-cast samples Fe
83Al
17
Fe83Ga
17
Fe79Al
21
Fe79Ga
21
Fe87Al
9Ga
4
Mag
netiz
atio
n (A
m2 /k
g)
Applied Field (T)
M-H loops of Fe-Ga, Fe-Al and Fe-Ga-Al thin plates (12*6*0.5 mm)in the as-cast state.
-0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8-200
-150
-100
-50
0
50
100
150
200
Thin plates - 12*6*0.5 mm - as-cast Fe
83Al
17
Fe79Al
21
Fe75Al
25
Fe70Al
30
Mag
netiz
atio
n (A
m2 /k
g)
Applied Field (T)
Magnetic BehaviorMagnetic Behavior
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
MM--T and MT and M--H curvesH curves
0 100 200 300 400 500 600 700 8000
20
40
60
80
100
120
140
160
180
M
agne
tizat
ion
(Am
2 /kg)
T (0C)
Fe1-x
Gax melt-spun ribbons
(vrotating wheel
= 35 m/sec) x = 0.175 x = 0.195 x = 0.21
Heating rate = 200C/min
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
-150
-100
-50
0
50
100
150
Mag
netiz
atio
n (A
m2 /k
g)
Applied field (T)
Fe1-x
Gax melt-spun ribbons
(vrotating wheel
= 35 m/sec)(as-quenched state)
x = 0.175 x = 0.195
The thermomagnetic measurements confirm the existence of bcc Fe (A2 phase), with an additional magnetic transition at around 5000C for Fe79Ga21melt-spun ribbons.
Very soft magnetic materials.
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
0.2 0.3 0.4 0.5 0.6 0.7 0.825
30
35
40
45
50
55
60
65
Fe83
Ga17
Fe79
Al21
Fe75
Al25
Fe70
Al30
λ s (pp
m)
Applied Field (T)
Magnetostriction versus applied magnetic field for Fe-Ga and Fe-Al thin plates (12*6*0.5 mm).
)(32
// ⊥−= λλλs
MagnetostrictionMagnetostriction
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
Magnetostriction as a function of the number of thin plates.
-0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8-40
-20
0
20
40
60
80
100
120
∆l/l
(µm
/m)
H (T)
Fe73
Al27
1 plate (40x5x1 mm)
5 plates (5 x 40x5x1 mm)
MagnetostrictionMagnetostriction
The magnetostriction is changing the sign from positive to negative when
the Al content increases.
0 5 10 15 20 25 30-30
-25
-20
-15
-10
-5
0
5
10
plate 12x6x0.5 mmH // with the long axis
∆l/l
(µm
/m)
Al content (at. %)
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
0.2 0.3 0.4 0.5 0.6 0.7 0.80
550
55
60
65
70
75
80
1 thin plate (40 * 5 * 1 mm) as-cast
5 thin plates glued together (40 * 5 * 1 mm) as-cast
Fe75
Al25
thin plates 1 thin plate (12 * 6 * 0.5 mm)
as-cast 1 thin plate (12 * 6 * 0.5 mm)
annealed @ 8000C/30' + 9000C/30' + 10000C/30' 1 thin plate (12 * 6 * 0.5mm)
annealed @ 9000C/120' + 10000C/120' + 11000C/120'
λ (p
pm)
Applied field (T)
Magnetostriction as a function of the thickness, number of thin plates measured at once and applied treatments.
MagnetostrictionMagnetostriction
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
-1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
0
10
20
30
40
50
60
70
80
Fe1-x
Gax cast bars
10 x 3 x 3 mm3
(as-quenched state) x = 0.175 x = 0.195
H parallel with the long axis
∆l/l
(x 1
0-6)
H (T)
Very soft magnetic materials.
Low magnetic fields to achieve the saturation magnetostriction.
H parallel with the bars long axis (casting axis).
MagnetostrictionMagnetostriction
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
The value of λs increases gradually to 160÷180 ppm, depending on composition (the maximum value is smaller for
higher contents of Ga), when applying an external compressive stress of 3÷5 MPa. Over this compressive stress value, the strain remains constant.
Strain vs. force (stress)Strain vs. force (stress)
0 5 10 15 20 25 300
20
40
60
80
100
120
140
160
180
Hmax, //
= 0.8 T
Def
orm
atio
n (p
pm)
compressive stress (kg)
Fe82.5
Ga17.5
(10 x 3 x 3 mm3) as-cast thermally treated
(10000C for 72h; slow cooling to 8000C; rapid cooling to RT) thermally treated
(10000C for 72h; slow cooling to RT)
Paper DR-09, MMM Conference, Tampa, FL, 5-9 November 2007
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
� Fe100-xGax (x = 17; 20) and Fe100-xAlx (x = 20; 24) nanopowders prepared by arc-discharge method;� nanopowders embedded in Poxipol® commercial resin (resistance to water, outdoor conditions and many corrosive agents), CTM polymer, electrostrictive polymers and polyurethane;� different concentrations (10 ÷ 30 wt. %) of metallic nanopowders into the resin layer (t = 3 ÷ 5 mm);� magnetostriction of the composite layers measured by the electrical resistance strain gauge technique.
FeFe--GaGa and Feand Fe --Al composites Al composites –– Samples PreparationSamples Preparation
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
FeFe--GaGa and Feand Fe --Al composites Al composites -- NanopowdersNanopowders PreparationPreparation
Arc discharge (modified Kratschmer-Huffman carbon arc method)
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
26415476812.31.26σs (emu/g)
198359352440425323386Nanopowders average size (nm)*
Fe76Al24Fe80Al20Fe80Ga20Fe83Ga17Composition
FeFe--GaGa and Feand Fe --Al composites Al composites -- NanopowdersNanopowders characterizationcharacterization
* The size distribution of nanoparticles was determined by Dynamic Light Scattering (DLS) technique, using a MICROTRAC Nanotrac 252 Particle Size Analyser.
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
Ni nanoparticles size is ranging between 250 and 500 nm.
-0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8-70
-60
-50
-40
-30
-20
-10
0
10
20
30
40
∆l
/l (µ
m/m
)
H (T)
Ni77
R23
(wt. %) (Fe80Ga20)
28R
72 (wt. %)
(Fe80Al20)11
R89
(wt. %) (Fe76Al24)
10R
90 (wt. %)
FeFe--GaGa and Feand Fe --Al composites Al composites -- MagnetostrictionMagnetostriction
Nanopowders embedded in Poxipol® resin.
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
-0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8
-80
-70
-60
-50
-40
-30
-20
-10
0
10
∆l/l
(µm
/m)
H (T)
CTM + Fe80
Al20
(1.36%) CTM + Fe
80Al
20 (2.79%)
CTM + Fe80
Al20
(2.91%) polyurethane + Fe
80Al
20 (20%)
Nanopowders embedded in CTM and polyurethane
-0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8-12
-10
-8
-6
-4
-2
0
2
∆l/l
(µm
/m)
H (T)
CTM + Fe76
Al24
(?%)
FeFe--GaGa and Feand Fe --Al composites Al composites -- MagnetostrictionMagnetostriction
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
(Co,Ni)-Mn-(Ga,Al) system
- melt-spun ribbons (25 µm thickness)
- 3-D bulk shaped samples (12 x 6 x 0.5 mm)
- composites
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
SEM images taken on the cross-section of the Co38Ni33Al29 thin plate.
The images do not indicate any preferential direction of the grains.
Ag resin
Ribbons long axis
Electrons beam
Cross-section
Free surface
Cu-wheel contact surface
Al support
ribbon
SEM images taken on the cross-section of the Co38Ni33Al29melt-spun ribbons.
Samples morphologySamples morphology
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
-1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
-5
0
5
10
15
20
25
30
35
40
45
50
55Plates (12x5x0.5 mm)H parallel
∆l/l
(ppm
)
H (T)
Ni50
Mn25
Ga25
Co50
Ni25
Ga25
Co38
Ni33
Al29
λλλλλλλλ--H and MH and M--H curves for H curves for NiMnGaNiMnGa , , CoNiGaCoNiGa and and CoNiAlCoNiAl thin platesthin plates
-0.75 -0.50 -0.25 0.00 0.25 0.50 0.75-50
-40
-30
-20
-10
0
10
20
30
40
50 H // with the long axis of the plates
Mag
netiz
atio
n (A
m2 /k
g)
H (T)
Ni50
Mn25
Ga25
Co50
Ni25
Ga25
Co38
Ni33
Al29
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
-1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
-5
0
5
10
15
20
25
30
35
40
45
50
55Plates (12x5x0.5 mm)H parallel
∆λ/λ
(pp
m)
H (T)
Ni50
Mn25
Ga25
Co50
Ni25
Ga25
Co38
Ni33
Al29
-1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
-5
0
5
10
15
∆λ/λ
(pp
m)
H (T)
Ni50
Mn25
Ga25
H parallel H perpendicular
-1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0-5
0
5
10
15
∆λ/λ
(pp
m)
H (T)
Co38
Ni33
Al29
H parallel H perpendicular
-1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
0
10
20
30
40
50
∆λ/λ
(pp
m)
H (T)
Co50
Ni25
Ga25
H parallel H perpendicular
λλλλλλλλ--H curves for H curves for NiMnGaNiMnGa , , CoNiGaCoNiGa and and CoNiAlCoNiAl thin platesthin plates
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
-1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0-5
0
5
10
15
20
25
30
H parallel
∆λ/λ
(pp
m)
H (T)
Co38
Ni33
Al29
20 melt-spun ribbons glued together plate 12x5x0.5 mm
-1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0-25
0
25
50
75
100
125
150
175
200
225
Co38
Ni33
Al29
20 melt-spun ribbons
∆λ/λ
(pp
m)
H (T)
H parallel with the ribbons long axis H perpendicular on the ribbons long axis H perpendicular on the ribbons plane
Magnetostriction as a function of the sampleMagnetostriction as a function of the sample ’’s shape and s shape and direction of the applied fielddirection of the applied field
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania
Despite the fact that λs is not comparable with Terfenol-D values, there are other important facts which can be considered for applications:
a. all samples are polycrystalline,
b. easy to prepare and reproducible (efficient and low cost),
c. not fragile and brittle,
d. the magnetoelastic properties can be further improved by tailoring the composition and treatment to be applied.
ConclusionsConclusions
Potential applications: in aeronautics and automotive industry
European School on Magnetism / Workshop on Advanced Magnetic MaterialsSeptember 9-18, 2007 ● Cluj-Napoca, Romania