Structural, Thermal and Magnetic Characterization of Ni-Mn-Ga Ferromagnetic Shape Memory Alloys

Rani, Ritu; Pandi, R. Senthur; Seenithurai, S.; Kumar, Sandeep; Meiyappan, Muthuraman; Mahendran, M.

doi:10.5923/j.ajcmp.20110101.01

Cited by 9 publications

(4 citation statements)

References 31 publications

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“…Moreover, for this transformation, the angle between the two vectors a and b remains unchanged: a • b = a • b . Using Expression (19), a 180-degree rotation relative to the k 1 axis can be described by the orthogonal tensor O(k…”

Section: A Monotwin Crystalmentioning

confidence: 99%

“…However, such materials can be not only isotropic but also textured. The structures of polycrystals, which originate from single twin crystals of Ni-Mn-Ga alloys and correspond to different textures, are described in many works (see, for example, [15][16][17][18][19]. We will use this information while modeling the behavior of polycrystalline material based on the behavior of single crystals.…”

Section: Introductionmentioning

confidence: 99%

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Microstructural Model of Magnetic and Deformation Behavior of Single Crystals and Polycrystals of Ferromagnetic Shape Memory Alloy

Rogovoy

Stolbova

2023

Magnetochemistry

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In this article, a microstructural model of the Heusler alloy with the shape memory effect caused by the application of an external magnetic field is constructed. The dynamics of the magnetization process are described using the Landau–Lifshitz–Gilbert equation. For the numerical implementation of the model using the finite element method, the variational equations corresponding to the differential formulation of the magnetic problem are used. Such an approach makes it possible to reduce (weaken) the requirements for the smoothness of the sought solution. The problem of magnetization of single crystals of the Ni2MnGa alloy, which has a “herringbone”-type martensitic structure (a twinned variant of martensite), is considered. In each element of the twin, the magnetic domains with walls of a certain thickness are formed. The motion and interaction of these walls and the rotation of magnetization vector in the walls and domains under the action of the external differently directed magnetic fields are studied. These processes in the Heusler alloy are also accompanied by the detwinning process. A condition for the detwinning of a ferromagnetic shape memory alloy in a magnetic field is proposed, and the effect of the reorientation (detwinning) of martensitic variants forming a twin on the magnetization of the material and the occurrence of structural (detwinning) deformation in it are taken into account. First, the processes of magnetization and structural deformation in a single grain are considered at different angles between the anisotropy axes of twinned variants and the external magnetic field. For these cases, the magnetization curves are constructed, and the deformed states are identified. The model described such experimental facts as the detwinning process and the jump in magnetization on these curves as a result of this process. It was shown that the jump occurred at a certain magnitude of the strength of the applied external magnetic field and a certain direction of its action relative to the twinning system. Then, based on the obtained results, deformed states arising due to the detwinning process were determined for various (isotropic and texture-oriented) polycrystalline samples, and magnetization curves taking into account this process were constructed for these materials.

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Section: A Monotwin Crystalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microstructural Model of Magnetic and Deformation Behavior of Single Crystals and Polycrystals of Ferromagnetic Shape Memory Alloy

Rogovoy

Stolbova

2023

Magnetochemistry

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“…A number of works are devoted to the investigation of the structure and properties of such polycrystalline samples. In works [15][16][17][18][19], the singletwinned crystals of Ni-Mn-Ga alloys and a polycrystal created from these elements are studied and magnetization curves for these structures are constructed.…”

Section: Introductionmentioning

confidence: 99%

Microstructural Modeling of the Magnetization Process in Ni2MnGa Alloy Polytwin Crystals

Rogovoy

Stolbova

2022

Magnetochemistry

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In this article, based on the theory of micromagnetism, a microstructural model of the behavior of the Heusler alloy in a magnetic field is constructed. The dynamics of the magnetic process is described by the Landau–Lifshitz–Gilbert equation. Using the Galerkin procedure, variational equations corresponding to the differential relations of the magnetic problem are written out. For numerical simulation, we consider the problem of magnetization of a Ni2MnGa alloy polytwin crystals, each grain of which is a twinned variant of martensite and has pronounced anisotropic properties. First, we consider the process of magnetization of a single grain, when an external magnetic field is applied at different angles to the anisotropy axes of twinned variants, and then, based on the results obtained, we plot magnetization curves for various (isotropic and texture-oriented) polycrystalline samples. This paper does not consider the process of detwinning, which can occur in such a material during the magnetization at a sufficiently high external field strength.

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“…The conventional thermo elastic shape memory alloys (SMAs) such as Ti-Ni alloys show the evidence of high value of strain but usually they have less actuation speed, which is limited by the heating/cooling rates. In the literature [2][3][4][5][6], various types of FSMA alloys were studied for phase transformation, structural and magnetic properties. In this paper, the Co-Ni-Al FSMA alloy has been studied, which is known for its high ductility, wide range of martensitic transformation temperature and phase transformation.…”

Section: Introductionmentioning

confidence: 99%

Comparative study of conventionally sintered Co-Ni-Al alloy with spark plasma sintered alloy

Arputhavalli

Agilan²,

Manandhar

et al. 2018

SCI SINTER

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Co-Ni-Al alloy samples were prepared by compacting the powdered alloy at various pressures in proper stoichiometric ratio and the high density compacted alloy was sintered at 673 K. The magnetic, mechanical properties, microstructure and phase analysis were studied and compared with that of spark plasma sintered (SPS) alloy. The sintered alloy exhibit martensitic twin variants with β phase structure. Along with the diffused particle, few agglomerated clusters were observed on the topographic images. The magnetic and the mechanical studies of the test specimens were investigated using the vibrating sample magnetometer, pin on disk tribometer and universal testing machine respectively. The coercivity value and the ductility of the SPS alloy are higher than the same of the as-sintered alloy.

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Structural, Thermal and Magnetic Characterization of Ni-Mn-Ga Ferromagnetic Shape Memory Alloys

Cited by 9 publications

References 31 publications

Microstructural Model of Magnetic and Deformation Behavior of Single Crystals and Polycrystals of Ferromagnetic Shape Memory Alloy

Microstructural Model of Magnetic and Deformation Behavior of Single Crystals and Polycrystals of Ferromagnetic Shape Memory Alloy

Microstructural Modeling of the Magnetization Process in Ni2MnGa Alloy Polytwin Crystals

Comparative study of conventionally sintered Co-Ni-Al alloy with spark plasma sintered alloy

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