Giant field-induced reversible strain in magnetic shape memory NiMnGa alloy

Heczko, Oleg; Sozinov, A.; Ullakko, K.

doi:10.1109/20.908764

Cited by 344 publications

(235 citation statements)

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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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“…While near stoichiometric Ni 2 MnGa shows cubic L2 1 symmetry in the austenitic phase, the structure of martensitic phase depending on temperature and exact composition are referred as (pseudo-)tetragonal or orthorhombic and can exhibit a modulation. The modulation means a shuffle of (110) planes of L2 1 structure in [1][2][3][4][5][6][7][8][9][10] direction with different periodicity [6]. Modulation with a periodicity of ten lattice planes (10M) or even fourteen lattice planes (14M) has been reported for structures with c/a < 1, which exhibits the MFIS of 6% [7,8] or 10%, respectively [9].…”

Section: Introductionmentioning

confidence: 99%

“…The modulation means a shuffle of (110) planes of L2 1 structure in [1][2][3][4][5][6][7][8][9][10] direction with different periodicity [6]. Modulation with a periodicity of ten lattice planes (10M) or even fourteen lattice planes (14M) has been reported for structures with c/a < 1, which exhibits the MFIS of 6% [7,8] or 10%, respectively [9]. The third martensitic phase observed in Ni-Mn-Ga alloys has non-modulated (NM) tetragonal structure with (c/a) NM § 1.17-1.23, which can be described as bodycentered tetragonal unit cell L1 0 [10].…”

Section: Introductionmentioning

confidence: 99%

Ab initiostudy of Ni₂MnGa under shear deformation

Zelený

Straka

Sozinov

2015

MATEC Web of Conferences

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Abstract. The effect of shear deformation on Ni2MnGa magnetic shape memory alloy has been investigated using ab initio electronic structure calculations. We used the projector-augmented wave method for the calculations of total energies and stresses as functions of applied affine shear deformation. The studied nonmodulated martensite (NM) phase exhibits a tetragonally distorted L21 structure with c/a > 1. A large strain corresponding to simple shears in <100>{001}, <001>{100} and <010>{100} systems was applied to describe a full path between two equivalent NM lattices. We also studied <10-1>{101} shear which is related to twining of NM phase. Twin reorientation in this system is possible, because applied positive shear results in path with significantly smaller energetic barrier than for negative shear and for shears in other studied systems. When the full relaxation of lattice parameters is allowed, the barriers further strongly decrease and the structures along the twinning path can be considered as orthorhombic.

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“…The proposed Gibbs free energy and the general constitutive equations for FIVR are described in §6a. Experiments, related to these material systems, are mostly performed under two-dimensional magneto-mechanical loading conditions (see [51,52]) and motivated by experiments, a reduced form of the constitutive equations is presented in §6a(iv). The calibration of material parameters, a 5 , b 4 , b 10 , c 14 , a 1 , a 11 , a 3 , b 1 , b 2 , c 14 for this simple loading conditions can be found in [33,53].…”

Section: Numerical Examplesmentioning

confidence: 99%

Constitutive modelling of magnetic shape memory alloys with discrete and continuous symmetries

Haldar

Lagoudas

2014

Proc. R. Soc. A.

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A free energy-based constitutive formulation is considered for magnetic shape memory alloys. Internal state variables are introduced whose evolution describes the transition from reference state to the deformed and transformed one. We impose material symmetry restrictions on the Gibbs free energy and on the evolution equations of the internal state variables. Discrete symmetry is considered for single crystals, whereas continuous symmetry is considered for polycrystalline materials.

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Giant field-induced reversible strain in magnetic shape memory NiMnGa alloy

Cited by 344 publications

References 6 publications

Energy absorption in Ni-Mn-Ga-polymer composites

Energy absorption in Ni-Mn-Ga-polymer composites

Ab initiostudy of Ni₂MnGa under shear deformation

Constitutive modelling of magnetic shape memory alloys with discrete and continuous symmetries

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Giant field-induced reversible strain in magnetic shape memory NiMnGa alloy

Cited by 344 publications

References 6 publications

Energy absorption in Ni-Mn-Ga-polymer composites

Energy absorption in Ni-Mn-Ga-polymer composites

Ab initiostudy of Ni2MnGa under shear deformation

Constitutive modelling of magnetic shape memory alloys with discrete and continuous symmetries

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Product

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Ab initiostudy of Ni₂MnGa under shear deformation