Bulk and thin films of magnetic shape memory Ni–Mn–Ga alloys deposited by multi-dipolar plasma-assisted sputtering

Girard, Geneviève; Béchu, Stéphane; Caillault, Nathalie; Carbone, Laurent; Ortéga, L.; Fruchart, D.

doi:10.1016/j.jallcom.2007.11.087

Cited by 10 publications

(6 citation statements)

References 15 publications

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“…While combinatorial studies provide ample information, including the stability range of the martensite phase and ferromagnetic ordering, the substrate constrains the films, thus shifting phase boundaries. Further Ni‐Mn‐Ga film fabrication methods include pulsed laser deposition,132, 133 laser beam ablation,134 flash evaporation of alloy powders,135 and multi‐dipolar plasma‐assisted sputtering, which may be performed with multiple alloy targets 136…”

Section: Three‐dimensional Aggregates and Constructsmentioning

confidence: 99%

Size Effects on Magnetic Actuation in Ni‐Mn‐Ga Shape‐Memory Alloys

2010

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The off-stoichiometric Ni(2)MnGa Heusler alloy is a magnetic shape-memory alloy capable of reversible magnetic-field-induced strains (MFIS). These are generated by twin boundaries moving under the influence of an internal stress produced by a magnetic field through the magnetocrystalline anisotropy. While MFIS are very large (up to 10%) for monocrystalline Ni-Mn-Ga, they are near zero (<0.01%) in fine-grained polycrystals due to incompatibilities during twinning of neighboring grains and the resulting internal geometrical constraints. By growing the grains and/or shrinking the sample, the grain size becomes comparable to one or more characteristic sample sizes (film thickness, wire or strut diameter, ribbon width, particle diameter, etc), and the grains become surrounded by free space. This reduces the incompatibilities between neighboring grains and can favor twinning and thus increase the MFIS. This approach was validated recently with very large MFIS (0.2-8%) measured in Ni-Mn-Ga fibers and foams with bamboo grains with dimensions similar to the fiber or strut diameters and in thin plates where grain diameters are comparable to plate thickness. Here, we review processing, micro- and macrostructure, and magneto-mechanical properties of (i) Ni-Mn-Ga powders, fibers, ribbons and films with one or more small dimension, which are amenable to the growth of bamboo grains leading to large MFIS, and (ii) "constructs" from these structural elements (e.g., mats, laminates, textiles, foams and composites). Various strategies are proposed to accentuate this geometric effect which enables large MFIS in polycrystalline Ni-Mn-Ga by matching grain and sample sizes.

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Section: Three‐dimensional Aggregates and Constructsmentioning

confidence: 99%

Size Effects on Magnetic Actuation in Ni‐Mn‐Ga Shape‐Memory Alloys

2010

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“…Nevertheless, Ni-Mn-Ga alloys are very brittle, which remarkably impedes their practical applications. To overcome the problem, several forms based on the alloy have been proposed and investigated, including thin films [5][6][7][8][9], ribbons [10][11][12] and composites consisting of ductile polymer matrix and Ni-Mn-Ga alloy particles [13][14][15][16][17][18][19][20]. Among these forms, the composites prepared by mixing Ni-Mn-Ga alloy particles and polymer matrix exhibit great advantages with good formability and low cost of production, compared with the thin films and ribbons which are often restricted by their dimension in applications.…”

Section: Introductionmentioning

confidence: 99%

Phase transition of Ni–Mn–Ga alloy powders prepared by vibration ball milling

Tian

Chen

Tong

et al. 2011

Journal of Alloys and Compounds

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“…In this study, we report for the first time on the electrodeposition of NiMnGa alloys from aqueous solutions. So far, NiMnGa thin films have been fabricated using PVD techniques such as magnetron sputtering [7,8,41], plasma assisted sputtering [42], pulsed laser deposition [43], laser beam ablation [44]. Only one report discusses the electrodeposition of layers of Ni, Mn and Ga from three different aqueous electrolytes [5].…”

Section: Introductionmentioning

confidence: 99%

Single step electrosynthesis of NiMnGa alloys

Özkale

Mushtaq

Fornell

et al. 2016

Electrochimica Acta

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A B S T R A C TAn electrochemical synthesis route for NiMnGa alloys is presented. Thin films of NiMnGa were fabricated by single step electrodeposition from aqueous electrolytes using direct current over a range of current densities. By electrolyte tuning, homogeneous films with high Ga and Mn content could be achieved at current densities as high as À400 mA cm À2 . Detailed compositional analysis of the alloys showed that growth was homogeneous and oxygen content was minimized. Films plated at very low current densities were found to be nanocrystalline/amorphous. In order to obtain fully crystalline samples, thermal annealing was carried out. Mechanical characterization was assessed by nanoindentation, and the effect of Ga content on mechanical properties was investigated.

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Bulk and thin films of magnetic shape memory Ni–Mn–Ga alloys deposited by multi-dipolar plasma-assisted sputtering

Cited by 10 publications

References 15 publications

Size Effects on Magnetic Actuation in Ni‐Mn‐Ga Shape‐Memory Alloys

Size Effects on Magnetic Actuation in Ni‐Mn‐Ga Shape‐Memory Alloys

Phase transition of Ni–Mn–Ga alloy powders prepared by vibration ball milling

Single step electrosynthesis of NiMnGa alloys

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