Reversible structural transition in monocrystalline Ni2FeGa microwires for shape-memory applications

Frolova, L. S.; Ryba, T.; Gamcová, J.; Milkovič, Ondrej; Diko, P.; Kavečanský, V.; Kravčák, J.; Vargová, Zuzana; Varga, R.

doi:10.1016/j.mseb.2020.114891

Cited by 4 publications

(4 citation statements)

References 29 publications

(29 reference statements)

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Section: Heusler Nanowires With High Spin Polarizationmentioning

confidence: 99%

“…It is possible to produce a very homogeneous microwire showing a single‐crystal structure along its entire length. [ 156 ] Moreover, it shows phase transition within the 240–290 K temperature range. [ 157 ] Since the composition of produced samples is very controllable in the case of Ni–Fe–Ga microwire, the transition temperature can be adjusted by adequately selected chemical composition.…”

Section: Heusler Microwiresmentioning

confidence: 99%

“…As given earlier, the Ni 2 FeGa microwire showed a single crystal structure along the entire wire. [ 156 ] Moreover, the <111> axis was oriented along the microwire's axis, enhancing the lattice variation during phase transition. This leads to the 2% of reversible straining within the temperature range 220–260 K directly after production without the necessity of further thermal treatment.…”

Section: Heusler Microwiresmentioning

confidence: 99%

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Heusler‐Based Cylindrical Micro‐ and Nanowires

Hennel

Varga

Frolova

et al. 2022

Physica Status Solidi (a)

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Heusler alloys present a large group of binary, [1][2][3][4][5] ternary, [6][7][8][9][10] or quaternary [11][12][13][14] compounds with a wide variety of physical properties. [15][16][17][18] Thanks to their extensive tunability [19][20][21][22] based on their chemical composition, crystal, or electronic structure, [23][24][25][26][27][28][29] they attract interest in the fundamental and application approach. [30][31][32][33][34] Particularly, spin polarization, [33,35] superconductivity, [36][37][38][39] shape memory, [40][41][42][43][44][45] or magnetocaloric behavior [28,40,[46][47][48][49][50] have triggered significant interest in the experimental and theoretical perspective.Based on the chemical composition and the resulting properties, Heusler alloys, also known as full-Heusler alloys with the stoichiometry X 2 YZ, can be divided into several groups according to their physical properties. [51] Co 2 YZ-based Heusler can be considered the leading group of materials showing high spin polarization (P) or even half metallicity (P ¼ 100%). [52][53][54][55][56][57] However, theoretical and experimental studies point to the high sensitivity of spin polarization on the structural disorder. [58] Here, the L2 1 crystalline phase exhibits the highest structural ordering, essential for achieving the required spin polarization values. [59] In contrast, while the mutual exchange of the atoms on the Y-Z position (B2 disorder) has a low influence on the spin polarization values, the X-Y or X-Y-Z disorders (D0 3 or A2, respectively) may significantly decrease spin polarization values. [55,60,61] The presented disadvantage can be solved by a suitable chemical composition or a proper method of preparation of Heusler alloys. [62,63] Stoichiometric and off-stoichiometric Ni-Mn-Z- [64][65][66] and Ni-Fe-Z-based Heusler alloys [67][68][69] are well-known magnetocaloric, shape memory, or even magnetic shape memory materials. [70,71] The mentioned Heusler alloys undergo a structural transformation from a low-temperature martensitic phase to a high-temperature austenitic phase, [51,[64][65][66][72][73][74] which may significantly influence the magnetic entropy change ΔS M and the intensity of the magnetocaloric effect. [75,76] Additionally, Heusler alloys consist of cheap elements like Ni, Fe, Mn, Co, Ga, and In, and thus may be considered low-cost counterparts for typical magnetocaloric material based on Gd, Rh, or other rare-earth elements. [77][78][79][80][81] Another advantage of the Ni-Mn-Zand Ni-Fe-Z-based Heusler alloys consists in the tunability of their structural and magnetic properties. Depending on the

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Section: Heusler Nanowires With High Spin Polarizationmentioning

confidence: 99%

Section: Heusler Microwiresmentioning

confidence: 99%

Section: Heusler Microwiresmentioning

confidence: 99%

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Heusler‐Based Cylindrical Micro‐ and Nanowires

Hennel

Varga

Frolova

et al. 2022

Physica Status Solidi (a)

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“…The ferromagnetic shape memory alloys with the martensitic transformation have been identified as an important field of research [1][2][3][4][5]. Over the years, they have attracted more and more attention with their intriguing mechanical [6][7][8][9][10], electromagnetic [11,12], and transport [13] properties, * Author to whom any correspondence should be addressed. making them suitable for potential applications in medicine, engineering, aerospace, or automobiles [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Fe–Mn–Ga shape memory glass-coated microwire with sensing possibilities

Galdun¹,

Vidyasagar²,

Hennel³

et al. 2021

J. Phys. D: Appl. Phys.

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The structural phase transformation in a non-stoichiometric shape memory Fe 42.8 Mn 27.6 Ga 29.6 Heusler glass-coated microwire was experimentally observed using indirect magnetic, permeability, and electrical resistance measurements. While the temperature dependence of magnetization revealed hysteresis of magnetization during the heating and cooling process, magnetic hysteresis loops point to the change in the direction of the easy magnetization axis of the low-and high-temperature phase. Additionally, the unusual behavior of the permeability and electrical resistance measurements are in good agreement with the magnetic measurements. The x-ray diffraction profile measured at room temperature revealed the coexistence of a high-temperature L2 1 phase (a = 5.88 Å) and low-temperature phase with the L1 2 structure (a = 3.71 Å) and can be considered as another proof of the shape memory effect that is expected in the Fe-Mn-Ga-based Heusler alloys. In the presented glass-coated microwire, it is not only possible to shift the transformation temperature with the external magnetic field, but from its initial permeability value, it is possible to determine whether the alloy has undergone the structural transformation. Therefore, the presented Fe-Mn-Ga-based glass-coated microwire may be considered a suitable candidate for microactuators with sensory capabilities.

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