Large field-induced strains in ferromagnetic shape memory materials

James, Richard D.; Tickle, R.S.; Wuttig, Manfred

doi:10.1016/s0921-5093(99)00364-0

Cited by 132 publications

(73 citation statements)

References 4 publications

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“…However, in 1996 a strain comparable to the best magneto-elastic materials was observed in a single crystal of off-stoichiometric Ni 2 MnGa, for a field of less than one Tesla [6]. The strain output reported in these alloys continued to increase, and by 2001 strains of up to 6% were reported in tetragonal single crystals of Ni-Mn-Ga [7,8,9,10,11,12]. Later 10% magnetically induced strain was reported in orthorhombic Ni-Mn-Ga [13].…”

Section: Contentsmentioning

confidence: 99%

Energy absorption in Ni-Mn-Ga-polymer composites

Feuchtwanger

Michael

Juang

et al. 2003

Journal of Applied Physics

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In recent years Ni-Mn-Ga has attracted considerable attention as a new kind of actuator material. Off-stoichiometric single crystals of Ni 2 MnGa can regularly exhibit 6% strain in tetragonal martensites and orthorhombic martensites have shown up to 10% strain when subjected to a magnetic field. These crystals are brittle and the production of single crystals can be quite costly. Terfenol-D, a commercially available giant-magnetostrictive material, suffers from some of the same drawbacks. It was found that composite materials made from Terfenol-D particles in a polymeric matrix could solve the issue of the brittleness while retaining a large fraction of the strain output of the alloy. At first glance a similar approach could be used to solve the brittleness issue of Ni-Mn-Ga, but the low blocking force of these alloys reduces the chances of achieving a Ni-Mn-Ga/polymer composite actuator. However, the stress-strain loops for Ni-Mn-Ga show a large mechanical hysteresis. This ability to dissipate energy makes this alloys very desirable for damping applications, and by putting particles of Ni-Mn-Ga in a composite, their brittleness becomes less of an issue.It is shown that by curing Ni-Mn-Ga/polymer composites under a magnetic field it is possible to align the particles in chains and to orient them so they will respond to a uniaxial load. The magnetic measurements show that there are twin boundaries in the particles that can be moved by an external stress. Stress-induced twin boundary motion in the particles is confirmed more directly by x-ray diffraction measurements, transmission electron microscope micrographs, and scanning electron microscope micrographs. Finally we demonstrate the ability of the Ni-Mn-Ga/polymer composites to dissipate mechanical energy when subjected to cyclic loads. The Ni-Mn-Ga/polymer composites can dissipate more than 70% of the energy they are given in every cycle, while pure polymer, Fe-filled and Terfenol-filled control samples dissipate less than 50% of the input energy in every cycle. The additional loss in these composites is shown to be due to the motion of twin boundaries. Simple numerical models reproduce the cyclic stress-strain behavior of the composites and explain non-conventional features observed in the Ni-Mn-Ga composites.

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Section: Contentsmentioning

confidence: 99%

Energy absorption in Ni-Mn-Ga-polymer composites

Feuchtwanger

Michael

Juang

et al. 2003

Journal of Applied Physics

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“…Meanwhile, the very small magnetic domains and comparatively large elastic twins of tetragonal phase were observed recently in some Ni-Mn-Ga alloys. 17,18) As far as a twinning period exceeds in this case the dimensions of magnetic domains, the magnetic field application results in the rotation of magnetic vectors inside the tetragonal martensite variants.…”

Section: General Considerationsmentioning

confidence: 99%

Magnetic-Field-Induced Stresses and Magnetostrain Effect in Martensite

et al. 2002

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An equivalence principle for mechanical and magnetoelastic stresses is used for the quantitative theoretical description of giant magnetostrain effect in ferromagnetic martensite. Field-induced strains are computed in the framework of phenomenological magnetoelastic model for two different orientations of magnetic field with respect to the crystal axes. Good agreement between the theoretical and experimental field dependencies of the strains in Ni-Mn-Ga alloys is achieved.

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“…Two alloy systems have predominantly demonstrated field-induced strain, 0.5% [2] in Fe-Pd and 6-10% [3][4][5][6][7] in Ni-Mn-Ga. Ni-Mn-Ga FSMA is focused among the different types of active materials because of their large field induced strain [8,9]. They show upto 10% strain response to an applied magnetic field by the twin boundary motion present in the martensite phase [7].…”

Section: Introductionmentioning

confidence: 99%

Structural, Thermal and Magnetic Characterization of Ni-Mn-Ga Ferromagnetic Shape Memory Alloys

Rani¹,

Pandi²,

Seenithurai³

et al. 2012

AJCMP

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Ni-Mn-Ga Ferromagnetic Shape Memory Alloys (FSMA) are highly interested in industrial actuators and energy harvesters because of its uniqueness in microstructure and multiple phases of these materials at different temperatures. The type of crystal structure, lattice parameters and magnetic properties depend on the alloy composition. The transformation and crystallographic properties are usually mapped to average number of valence electrons per atom. The present work deals with the fundamental characterization of single crystal and polycrystalline nature of these alloys. Though, the polycrystal shows low magnetic field induced stain (MFIS), the easy preparation techniques and cost effective aspects compared with the single crystals makes an impressive interest in dealing with that. The structural, thermal and magnetic parameters are observed and compared for these single and polycrystals.

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Large field-induced strains in ferromagnetic shape memory materials

Cited by 132 publications

References 4 publications

Energy absorption in Ni-Mn-Ga-polymer composites

Energy absorption in Ni-Mn-Ga-polymer composites

Magnetic-Field-Induced Stresses and Magnetostrain Effect in Martensite

Structural, Thermal and Magnetic Characterization of Ni-Mn-Ga Ferromagnetic Shape Memory Alloys

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