Mechanical and magnetic behavior of oligocrystalline Ni–Mn–Ga microwires

Zheng, Pai; Kucza, Nikole J.; Patrick, Charles L.; Müllner, Peter; Dunand, David C.

doi:10.1016/j.jallcom.2014.11.067

Cited by 43 publications

(18 citation statements)

References 37 publications

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“…As reviewed earlier, Qian et al [17] and Zhang et al [18] reported superelasticity in austenitic Ni-Mn-Ga wires by stress-induced martensitic-austenitic transformations on loading and unloading, and we reported superelastic behavior in Ni-MnGa wires by reversible inter-martensitic transformation [21]. By contrast, in the present work, we show that superelasticity is due to reversible martensitic variants reorientation without crystallographic transformation, albeit in a Ni-Mn-Ga wire which is richer in nickel than those in the above cited studies.…”

Section: Mechanism For Fluctuations and Superelasticitysupporting

confidence: 75%

“…Liu et al [20] investigated the effect of Ga substitution by Fe in melt-extracted Ni-Mn-Ga(Fe) wires on the thermal and magnetic (but not mechanical) properties. Recently, we created Taylor wires with composition of Ni 54.1 Mn 26.2 Ga 19.7 and martensitic bamboo grains, which, under an externally applied tensile stress, exhibit superelastic behavior with twinning stresses of 22-30 MPa and recoverable tensile strains up to 3.5%, which we speculated to be due to a reversible inter-martensitic transformation [21]. A 1 T magnetic field caused the wire to bend to a surface strain of 1.5%, and during field rotation, the wire deflected back and forth by reversible twinning, an effect called magnetic-torque-induced bending (MTIB).…”

Section: Introductionmentioning

confidence: 99%

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Superelasticity by reversible variants reorientation in a Ni–Mn–Ga microwire with bamboo grains

et al. 2015

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a b s t r a c tThe link between microstructure and mechanical properties is investigated for a superelastic Ni-Mn-Ga microwire with 226 lm diameter, created by solidification via the Taylor method. The wire, which consists of bamboo grains with tetragonal martensite matrix and coarse c precipitates, exhibits fully reversible superelastic behavior up to 4% tensile strain. Upon multiple tensile load-unload cycles, reproducible stress fluctuations of $3 MPa are measured on the loading superelastic stress plateau of $50 MPa. During cycles at various temperatures spanning À70 to 55°C, the plateau stress decreases from 58 to 48 MPa near linearly with increasing temperature. Based on in situ synchrotron X-ray diffraction measurements, we conclude that this superelastic behavior is due to reversible martensite variants reorientation (i.e., reversible twinning) with lattice rotation of $13°. The reproducible stress plateau fluctuations are assigned to reversible twinning at well-defined locations along the wire. The strain recovery during unloading is attributed to reverse twinning, driven by the internal stress generated on loading between the elastic c precipitates and the twinning martensite matrix. The temperature dependence of the twining stress on loading is related to the change in tetragonality of the martensite, as measured by X-ray diffraction.

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Section: Mechanism For Fluctuations and Superelasticitysupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Superelasticity by reversible variants reorientation in a Ni–Mn–Ga microwire with bamboo grains

et al. 2015

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“…Meanwhile, large MFIS is closely related to the existence of a long period modulated structure. Here, in order to overcome the intrinsic brittleness of Ni-Mn-Ga SMAs, the Taylor-Ulitovsky method was used to fabricate oligocrystalline structured microwires [35][36][37]. The rapid solidification process that caused by quenching the melt alloys may lead to a rich variety of microstructures and properties, which has already been observed before [38,39]…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Superlattice in austenitic Ni-Mn-Ga shape memory microwires

Ding

et al. 2019

Journal of Alloys and Compounds

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The link between microstructure evolution, micromodulated domain and the structure transformation of Ni-Mn-Ga shape memory microwires prepared with rapid solidification is studied systematically by TEM and HRTEM. Multiple microdomain structures are determined according to the corresponding diffraction spots. The domain structure with a periodic distortion is a kind of characteristic of premartensitic phase. When cooling below the martensitic transformation temperature, the austenitic phase transforms to modulated 5M martensite, and the sequence of phase transformation can finally be confirmed from austenite to premartensite to 5M martensite during cooling. The characterization of micromodulated domain and the structure characteristics of austenite at atomic scale provide comprehensive understanding on the martensitic phase transformation route.

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“…Then, the glass tube is softened due to its contact with the molten metal, and it can be drawn. Recently, this method has been modified and applied to create glass-coated Ni-Mn-Ga microwires with equiaxed cross section, as shown in Figure 9 [39,40].…”

Section: Ni-mn-ga Microwiresmentioning

confidence: 99%

Ferromagnetic Shape Memory Alloys: Foams and Microwires

Zhang¹,

Qian²

2017

Shape Memory Alloys - Fundamentals and Applications

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Ferromagnetic shape memory alloys exhibit martensite transformation (MT) and magnetic transition and thus may be actuated by thermal and magnetic fields. The working frequency of these alloys may be higher than conventional shape memory alloys, such as Ni-Ti, because the magnetic field may operate at higher frequency. This chapter focuses on some fundamental topics of these multifunctional materials, including the composition-structure relationship, the synthesis of the foams and microwires, the martensite transformation and magnetic transition characters, the properties (magneticfield-induced strain (MFIS), magnetocaloric effects (MCEs), shape memory effects, and superelastic effects), and applications. The improvement of the magnetic-field-induced strain due to the reduced constraint of twin boundary motion caused by grain boundaries in polycrystalline Ni-Mn-Ga foams and the size effects of the superelasticity and magnetocaloric properties in Ni-Mn-X (X = In, Sn, Sb) microwires are detailed and addressed.

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Mechanical and magnetic behavior of oligocrystalline Ni–Mn–Ga microwires

Cited by 43 publications

References 37 publications

Superelasticity by reversible variants reorientation in a Ni–Mn–Ga microwire with bamboo grains

Superelasticity by reversible variants reorientation in a Ni–Mn–Ga microwire with bamboo grains

Superlattice in austenitic Ni-Mn-Ga shape memory microwires

Ferromagnetic Shape Memory Alloys: Foams and Microwires

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