Magnetic, mechanical and fatigue properties of a Ni45.4Mn29.1Ga21.6Fe3.9 single crystal

Guldbakke, Jan Magnus; Chmielus, Markus; Rolfs, Katharina; Schneider, R.; Müllner, Peter; Raatz, Annika

doi:10.1016/j.scriptamat.2010.02.032

Cited by 16 publications

(6 citation statements)

References 16 publications

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“…Rotating-field experiments showed a change in magnetic-field-induced strain (MFIS) over the course of the fatigue tests. Samples which deformed well below their theoretical possible MFIS when actuated by a magnetic field, did not fail by fracture [19,20,[22][23][24][25][26] while samples deforming at or close to maximum theoretical MFIS did fracture [18][19][20]. X-ray tomography of cracks of a 10M Ni-Mn-Ga actuated magnetically for 10 8 cycles indicated fatigue cracks parallel to the {110} plane [24].…”

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confidence: 99%

Effects of Surface Pinning, Locking and Adaption of Twins on the Performance of Magnetic Shape-Memory Alloys

Chmielus

Müllner

2011

MSF

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We study the effect of surface modifications and constraints on the mechanical properties of Ni-Mn- Ga single crystals, which are imposed by (i) structural modifications near the surface, (ii) mounting to a solid surface, and (iii) guiding the stroke. Spark eroded samples were electropolished and characterized before and after each polishing treatment. Surface damage was then produced with spark erosion and abrasive wearing. Surface damage stabilizes and pins a dense twin-microstructure and prevents twins from coarsening. The density of twins increases with increasing degree of surface deformation. Twinning stress and hardening rate during mechanical loading increase with increasing surface damage and twin density. In contrast, when a damaged surface layer is removed, twinning stresses, hardening rate, and twin density decrease. Constraining the sample by mounting and guiding reduces the magnetic-field-induced strain by locking twins at the constrained surfaces. . For single-domain crystals and for hard magnetic shape-memory alloys, external constraints strongly reduce the magnetic-field-induced strain and the fatigue lifetime is short. In contrast, for selfaccommodated martensite and for soft magnetic shape-memory alloys, the twin-microstructure adapts well to external constraints and the fatigue lifetime is long. The performance of devices with MSMA transducers requires managing stress distributions through design and control of surface properties, microstructure, and constraints.

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confidence: 99%

Effects of Surface Pinning, Locking and Adaption of Twins on the Performance of Magnetic Shape-Memory Alloys

Chmielus

Müllner

2011

MSF

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“…A strain of 0.19% under a magnetic field of 0.43 T was obtained from a Ni 2 MnGa sample at 265 K. From then on, the interest of the MFIS in FSMAs grew rapidly all over the world. Besides, many different compositions, such as Ni-Fe-Ga [48], Ni-Mn-In [49], Co-Ni-Al [50], Co [51], Fe [52], and rare earth [53]-doped Ni-Mn-Ga alloys, have also been investigated.…”

Section: Overview Of Mfismentioning

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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“…These authors argue that: "The historical classification of martensitic modulated structures based on the number of observed satellites must be reconsidered". For many applications the shape memory materials should be able to operate at elevated temperatures above 130°C [34]. structural phase transition temperatures.…”

Section: Introductionmentioning

confidence: 99%

“…It was noticed that additional elements may essentially modify the transition temperature and enhance both shape memory and caloric effects. In particular, additions of Fe [34][35][36][37] and Cu [38,39] appeared very effective to shift the transition temperature and modify shape memory and magnetocaloric effects [40]. While in stoichiometric and off-stoichiometric ternary NMGs the martensite structures were studied relatively well, the structure of NMGs additionally doped with Fe and Cu is still poorly understood.…”

Section: Introductionmentioning

confidence: 99%

Multiscale twin hierarchy in NiMnGa shape memory alloys with Fe and Cu

Barabash

Popov

et al. 2015

Acta Materialia

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X-ray microdiffraction and scanning electron microscopy studies reveal 10 M martensitic structure with a highly correlated multiscale twin hierarchy organization in NiMnGaFeCu shape memory alloys. High compatibility is found at the twin interfaces resulting in a highly correlated twinned lattice orientation across several laminate levels. The lattice unit cell is described as monoclinic I-centered with a = 4.28 Å , b = 4.27 Å , c = 5.40 Å , c = 78.5°. The modulation is found parallel to the b axis. Thin tapered needle-like lamellae and branching are observed near the twin boundaries.

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Magnetic, mechanical and fatigue properties of a Ni45.4Mn29.1Ga21.6Fe3.9 single crystal

Cited by 16 publications

References 16 publications

Effects of Surface Pinning, Locking and Adaption of Twins on the Performance of Magnetic Shape-Memory Alloys

Effects of Surface Pinning, Locking and Adaption of Twins on the Performance of Magnetic Shape-Memory Alloys

Ferromagnetic Shape Memory Alloys: Foams and Microwires

Multiscale twin hierarchy in NiMnGa shape memory alloys with Fe and Cu

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