Ferromagnetic shape memory in the NiMnGa system

Tickle, R.S.; James, Richard D.; Shield, T. W.; Wuttig, Manfred; Кокорин, В. В.

doi:10.1109/20.799080

Cited by 206 publications

(128 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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“…Ni-Mn based Heusler alloys are magnetic materials that exhibit structural transformation of the martensitic type with large magnetic field induced strains and can be exploited for tremendous technological applications [1,2]. These materials also offer an excellent opportunity to investigate the various aspects of magnetic and structural phase transformations in a single system [3,4].…”

Section: Introductionmentioning

confidence: 99%

Local atomic arrangement and martensitic transformation in Ni₅₀Mn₃₅In₁₅: an EXAFS study

Bhobe¹,

Priolkar²,

Sarode³

2008

J. Phys. D: Appl. Phys.

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Abstract. Heusler alloys that undergo martensitic transformation in ferromagnetic state are of increasing scientific and technological interest. These alloys show large magnetic field induced strains upon martensitic phase change thus making it a potential candidate for magneto-mechanical actuation. The crystal structure of martensite is an important factor that affects both the magnetic anisotropy and mechanical properties of such materials. Moreover, the local chemical arrangement of constituent atoms is vital in determining the overall physical properties. Ni 50 Mn 35 In 15 is one such ferromagnetic shape memory alloy that displays exotic properties like large magnetoresistance at moderate field values. In this work, we present the extended xray absorption fine-structure measurements (EXAFS) on the bulk Ni 50 Mn 35 In 15 which reveal the local structural change that occurs upon phase transformation. The change in the bond lengths between different atomic species helps in understanding the type of hybridization which is an important factor in driving such Ni-Mn based systems towards martensitic transformation.

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“…5 Obviously, this property provides a technological value for Ni 2 MnGa, and a great deal of effort has been invested in research to understand the properties of the martensitic phase in this alloy. [6][7][8][9][10][11] Stoichiometric Ni 2 MnAl is structurally stable down to the lowest temperatures, but martensitic transformations occur in the slightly off-stoichiometric compounds, and their mechanical properties are more favorable than those of the relatively brittle Ni 2 MnGa. It is, therefore, thought that Ni 2 MnAl could be provided as an alternative material if its magnetic shape memory properties are as favorable as those of Ni 2 MnGa.…”

Section: Introductionmentioning

confidence: 99%

Coexisting ferro- and antiferromagnetism in Ni2MnAl Heusler alloys

Acet

Duman

Wassermann

et al. 2002

Journal of Applied Physics

132

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The structural and magnetic properties of stoichiometric Ni 2 MnAl are studied to clarify the conditions for ferromagnetic and antiferromagnetic ordering claimed to occur in this compound. X-ray and magnetization measurements show that although a single phase B2 structure can be stabilized at room temperature, a single L2 1 phase is not readily stabilized, but rather a mixed L2 1 ϩB2 state occurs. The mixed state incorporates ferromagnetic and antiferromagnetic parts for which close-lying Curie and a Néel temperatures can be identified from magnetization measurements.

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Ferromagnetic shape memory in the NiMnGa system

Abstract: Publisher hem Identiiier S OOi8-9464(99)07904-2. field below the austenite/martensite transformation temperature, and strains of 1.3% upon application of a field from

Cited by 206 publications

References 11 publications

Energy absorption in Ni-Mn-Ga-polymer composites

Energy absorption in Ni-Mn-Ga-polymer composites

Local atomic arrangement and martensitic transformation in Ni₅₀Mn₃₅In₁₅: an EXAFS study

Coexisting ferro- and antiferromagnetism in Ni2MnAl Heusler alloys

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Ferromagnetic shape memory in the NiMnGa system

Abstract: Publisher hem Identiiier S OOi8-9464(99)07904-2. field below the austenite/martensite transformation temperature, and strains of 1.3% upon application of a field from

Cited by 206 publications

References 11 publications

Energy absorption in Ni-Mn-Ga-polymer composites

Energy absorption in Ni-Mn-Ga-polymer composites

Local atomic arrangement and martensitic transformation in Ni50Mn35In15: an EXAFS study

Coexisting ferro- and antiferromagnetism in Ni2MnAl Heusler alloys

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Local atomic arrangement and martensitic transformation in Ni₅₀Mn₃₅In₁₅: an EXAFS study