Magnetically resettable 0.16% free strain in polycrystalline Ni–Mn–Ga plates

Pötschke, Martin; Weiß, Sandra; Gaitzsch, Uwe; Cong, Daoyong; Hürrich, C.; Roth, S.; Schultz, L.

doi:10.1016/j.scriptamat.2010.04.027

Cited by 53 publications

(29 citation statements)

References 15 publications

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“…Some pioneering work has been done to characterize the global microstructures and variant orientations of modulated martensite in Ni-Mn-Ga alloys [16][17][18][19][20]. It should be noted that the EBSD-based orientation determination requires the complete crystal structure information, including the lattice constants and the atomic position of each atom in the unit cell.…”

Section: Introductionmentioning

confidence: 99%

Twin relationships of 5M modulated martensite in Ni–Mn–Ga alloy

Zhang

Esling

et al. 2011

Acta Materialia

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Section: Introductionmentioning

confidence: 99%

Twin relationships of 5M modulated martensite in Ni–Mn–Ga alloy

Zhang

Esling

et al. 2011

Acta Materialia

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“…A strong texture, large grains and a mechanical training can decrease s twin . [4,5] The main disadvantage of single-and polycrystals is their complex preparation.An alternative to single-and polycrystals are Ni-Mn-Ga polymer composites. [6][7][8] Single crystalline particles embedded in a stiffness-matched polymer matrix allow overcoming the disadvantages.…”

mentioning

confidence: 99%

“…A strong texture, large grains and a mechanical training can decrease s twin . [4,5] The main disadvantage of single-and polycrystals is their complex preparation.…”

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confidence: 99%

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Reversible Magnetic Field Induced Strain in Ni₂MnGa‐Polymer‐Composites

et al. 2011

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Magnetic shape memory (MSM) alloys are a new class of materials for sensor and actuator applications. Ni-Mn-Ga single crystals show large magnetic-field induced strain (MFIS) in moderate magnetic fields below 1 T caused by reorientation of martensitic variants by twin boundary motion. The maximum possible strain e ¼ 1-(c/a) is given by the lattice parameters a and c of the martensite unit cell resulting in e ¼ 6% for 5M martensite and e ¼ 11% for 7M martensite. [1][2][3] However, the main disadvantage of single crystals is their high brittleness. One possible solution is the synthesis of textured polycrystalline Ni-Mn-Ga for which a MFIS of 1% has been reported. [4] Due to constraints by grain boundaries, the twinning stress s twin for moving twin boundaries is still much higher for polycrystals (s twin > 15 MPa) compared to that in single crystals (s twin < 2 MPa). A strong texture, large grains and a mechanical training can decrease s twin . [4,5] The main disadvantage of single-and polycrystals is their complex preparation.An alternative to single-and polycrystals are Ni-Mn-Ga polymer composites. [6][7][8] Single crystalline particles embedded in a stiffness-matched polymer matrix allow overcoming the disadvantages. A thin polymer film between the single crystalline particles allows the particles to strain und reduces s twin . Another advantage of composites is the decrease of eddy currents due to a non-conducting polymer matrix, which enables high frequency applications, and the simple preparation of textured bulk materials.In previous works, we showed that melt-extracted and subsequently annealed fibres exhibit a bamboo-like grain structure and an MFIS of 1%. [6] However, only small amount of grains in the fibre are active. Different crystallographic orientations of grains as well as still existing grain boundaries hinder activation of the whole fibre. A separation of fibres into nearly single crystalline particles by breaking them alongComposite materials consisting of magnetic shape memory alloy particles and a polymer matrix combine the advantages of both material classes: the high achievable magnetic field induced strain (MFIS) of 6% of Ni-Mn-Ga with a ductile matrix. Engineering the particle-matrix interface as well as matching stiffness of polymer matrix is of importance for achieving high reversible MFIS to use this material as actuator or damper. We investigated those properties for Ni 50.9 Mn 27.1 Ga 22.0 and Ni 50.3 Mn 24.6 Ga 25.1 polymer composites. Particles were produced by gently crushing melt-extracted and subsequently annealed fibres. At room temperature, the Ni 50.9 Mn 27.1 Ga 22.0 particles exhibit a 5M martensitic structure, while the Ni 50.3 Mn 24.6 Ga 25.1 particles are austenitic. These particles were embedded into the polymer, either a stiff epoxy resin or a soft polyurethane. In response to an external applied magnetic field, the particles tend to relocate within the polyurethane due to its very low Young's modulus and magnetostatic interaction between particles. Slightly stiffer pol...

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“…11 Generally, Ni-Mn-Ga FSMAs are highly brittle in nature, hindering their use in practical applications. To overcome the brittleness of Ni-Mn-Ga alloys, various innovative fabrication routes have been introduced, resulting in melt-spun ribbons, 12 foils, 13 nanostructured powder, 14 plates, 15 composites, 7 thin films, 16 and foams. 17 Among these, synthesis of Ni-Mn-Ga alloy in thin-film form with significant ductility is of great interest because such materials are promising candidates for use in microelectromechanical system (MEMS) applications, for example, microactuators and microvalves.…”

Section: Introductionmentioning

confidence: 99%

Structural and Magnetic Properties of Sputter-Deposited Polycrystalline Ni-Mn-Ga Ferromagnetic Shape-Memory Thin Films

Kumar

Seenithurai

Raja

et al. 2015

Journal of Elec Materi

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Polycrystalline Ni-Mn-Ga ferromagnetic shape-memory thin films have been deposited on Si (100) substrates using a direct-current magnetron sputtering technique. The microstructure and the temperature dependence of magnetic properties of the films have been investigated by x-ray diffraction, scanning electron microscopy, and thermomagnetic measurements. As-deposited Ni 50.2 Mn 30.6 Ga 19.2 film showed quasi-amorphous structure with paramagnetic nature at room temperature. When annealed at 873 K, the quasi-amorphous film attained crystallinity and possessed L2 1 cubic ordering with high magnetic transition temperature. Saturation magnetization and coercivity values for the annealed film were found to be 220 emu/cm 3 and 70 Oe, respectively, indicating soft ferromagnetic character with low magnetocrystalline anisotropy. The magnetic transitions of the film deposited at 100 W were above room temperature, making this a potential candidate for use in microelectromechanical system devices.

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Magnetically resettable 0.16% free strain in polycrystalline Ni–Mn–Ga plates

Cited by 53 publications

References 15 publications

Twin relationships of 5M modulated martensite in Ni–Mn–Ga alloy

Twin relationships of 5M modulated martensite in Ni–Mn–Ga alloy

Reversible Magnetic Field Induced Strain in Ni₂MnGa‐Polymer‐Composites

Structural and Magnetic Properties of Sputter-Deposited Polycrystalline Ni-Mn-Ga Ferromagnetic Shape-Memory Thin Films

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Magnetically resettable 0.16% free strain in polycrystalline Ni–Mn–Ga plates

Cited by 53 publications

References 15 publications

Twin relationships of 5M modulated martensite in Ni–Mn–Ga alloy

Twin relationships of 5M modulated martensite in Ni–Mn–Ga alloy

Reversible Magnetic Field Induced Strain in Ni2MnGa‐Polymer‐Composites

Structural and Magnetic Properties of Sputter-Deposited Polycrystalline Ni-Mn-Ga Ferromagnetic Shape-Memory Thin Films

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Reversible Magnetic Field Induced Strain in Ni₂MnGa‐Polymer‐Composites