NiTi AND NiMnGa NANOCRYSTALLINE SHAPE MEMORY ALLOYS AND COMPOSITES FOR NEXT GENERATION SENSORS AND A

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Ni-Ti AND Ni-Mn-Ga NANOCRYSTALLINE SHAPE MEMORY
ALLOYS AND COMPOSITES FOR NEXT GENERATION SENSORS
AND ACTUATORS

• Teodor M. Breczko
• Lab of Functional Materials and Nanotechnology
  of University of Warmia and Mazury, Olsztyn,
  Poland

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SHAPE MEMORY ALLOYS(SMA) Rapidly quenched
melt-spun ribbons of Ti-Ni, Ti50Ni50-xFex,
Ti50Ni50-yCoy and Ti50Ni50-zCuz shape memory
alloys were obtained and studied with the aid of
X-ray diffraction, TEM and magnetic
susceptibility and resistivity measurements. The
formation of amorphous, nanocrystalline, and
submicron-grained structures was demonstrated.
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The X-ray diffraction studies show that,
depending on the composition and the cooling
rate, the melt-quenched Ni-Ti-Cu alloys can be
prepared in the amorphous (curves 1,2), mixed
amorphous-nanocrystalline (3),and
submicrocrystallinestates (4,5).
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Experimental results
Changes in RMS micro-strains ? ?2?1/2 10-3 with
number of thermal and mechanical loading.
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High mechanical strength and plasticity of
rapidly quenched ribbons may be obtained
alongside with narrow temperature hysteresis of
the shape memory effect and high durability
necessary for a number of applications. The
Cu-doped melt-spun ribbons are found to be most
promising for sensors and actuators operating in
the vicinity of room temperature.
Temperature sensor on the base of Ti-Ni-Cu
melt-spun ribbon ring actuator with a diameter D
2 mm (movable contact not shown). Operation
temperature T 70oC.
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FERROMAGNETIC SHAPE MEMORY HEUSLER ALLOYS
(FSMA) Ferromagnetic Ni-Mn-Ga and Co-Ni-Ga
Heusler alloys attract attention due to their
unique combination of thermoelastic martensitic
transformation and ferromagnetism as well as
potential applications in new types of sensors
and actuators. Rapidly quenched ribbons (RQR) of
these alloys with nano- and microcrystalline
structure controlled by annealing are of interest
in connection with the possibility of their shape
memory control with the aid of magnetic field.
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FERROMAGNETIC SHAPE MEMORY HEUSLER ALLOYS
Ni2xMn1-xGa
TM
Partial substitution of Mn with Ni increases the
temperature of structural transition TM and
decreases the Curie temperature TC resulting in
their coincidence at x 0.19
TP
TC
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Observations in polarized light provide new
dimensions to the analysis of the martensite
structure. The optical contrast originates from
anistropic reflectance of martensite and depends
on the orientation of the crystal c-axis with
respect to the plane of light polarization.
Martensite structure at the surface of a
mechanically polished polycrystalline
Ni2.16Mn0.84Ga sample as observed in polarized
light
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Video showing the appearance and disappearance of
martensite phase in Ni2.16Mn0.84Ga alloy in the
course of cooling and heating
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martensite
austenite
Combined optical measurements of the deformation
and microstructural observations provide
information on the details of material behaviour
during phase transition
Microstructure of Ni2.16Mn0.84Ga at RT and at ?
370 ? Arrows and letters indicate the points of
intersection of martensite boundaries with a
rectangular reference grid on the sample surface
and their inflection on transition to the
austenite state
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OBSERVATION OF DS REALIGNMENT DURING
MARTENSITE-AUSTENITE TRANSFORMATION IN Ni-Mn-Ga
ALLOY (video film fragments)
Initially the Ni2.16Mn0.84Ga microcrystal is in
the martensitic state characterized by 180-degree
magnetic DS. On heating the alloy transforms
into a cubic magnetically soft austenite phase
with negligible stray fields on the sample
surface

• Sample size 200x800 mm

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Melt-spun Ni-Mn-Ga ribbons thickness 30 mm ,
length 10-30 mm
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SHAPE MEMORY EFFECT IN NANOCRYSTALLINE Ni-Mn-Ga
RIBBON
initial shape
after heating
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Simultaneous observation of the martensite and
magnetic domain structure of polycrystalline
texturized sample having elongated grains
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MAGNETICALLY CONTROLLED ACTUATORS BASED ON
Ni-Mn-Ga (ADAPTAMAT)
A5-2
A06-3
Displacement 0,6 5 mm, Force up to 1000
Newtons, Frequency 300 1000 Hz
A1-2000
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RESULTS

• 1. The new trend in magnetic shape memory control
  is developed on the basis of classical shape
  memory. The reversible martensitic transition by
  magnetic field at constant temperature is
  demonstrated.
• 2. One- and two way shape memory control of
  Ni-Mn-Fe-Ga nanocrystalline samples is shown. The
  recoverable strain 3 for one-way and 1,4 for
  two way shape memory is measured.
• 3. The results can be applied to MEMS, NEMS and
  MAGMAS devices design.

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THE TEAM
Laboratoire d'Electrotechnique de Grenoble,
France, (Dr. Orphee CUGAT) - application of
nanocrystalline materials in MAGMAS  
IMEM-CNR, Magnetic Materials Department, Parma,
Italy (Dr Franca ALBERTINI) - magnetic properties
of nanocrystalline materials
Dept. Fisica Unversitat de Girona, Spain (Dr.
Joan Josep SUNOL) - mechanical alloying of
nanocrystalline materials
A.F.Ioffe Institute, Russian Academy of Sciences
(Prof. V.I. BETEKHTIN) - structural studies  
Lab of Functional Materials and Nanotechnology of
University of Warmia and Mazury, Olsztyn, Poland
(Prof. T. BRECZKO) - X-ray, MFM
C.V.Kurdyumov Institute for Metal Physics and
Functional Materials, Moscow (Prof. A.M. GLEZER)
- thin film preparation  
Institute of Metal Physics of Ural Division of
Russian Academy of Sciences in Ekaterinburg
(Prof. V.G. PUSHIN) - electron microscopy)  
Institute of Powder Metallurgy, Minsk, Belarus (
Dr. N.M. CHIGRINOVA) - multilayered structures  
St Petersburg State Technical University (prof..
A. I. MELKER) - computer simulations
Institute of Radioelectronics, Russian Academy of
Sciences, Moscow (Prof. V.G. SHAVROV) composite
structures
Tver State University, Russia (Prof. R.M.
GRECHISHKIN), domain structure studies