The kinetics of phase transformations in ferromagnetic shape memory alloys Ni–Mn–Ga

Buchelnikov, V. D.; Bosko, S.I.

doi:10.1016/s0304-8853(02)01070-3

Cited by 18 publications

(13 citation statements)

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“…The experimental results obtained evidence that the ∆T dependence has a peak at T ≈ 340 K. This temperature corresponds A statistical model is suggested for the theoretical description of the alloy properties near MSPT. The model takes into account coexistence of three types of martensitic and one type of austenitic structural domains in the vicinity of MSPT point [3,4]. Each structural domain is divided by 180…”

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Magnetocaloric effect and magnetization in a Ni–Mn–Ga Heusler alloy in the vicinity of magnetostructural transition

Aliev

Batdalov

Bosko

et al. 2004

Journal of Magnetism and Magnetic Materials

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The magnetic and thermodynamic properties of a Ni2.19Mn0.81Ga alloy with coupled magnetic and structural (martensitic) phase transitions were studied experimentally and theoretically. The magnetocaloric effect was measured by a direct method in magnetic fields 0−26 kOe at temperatures close to the magnetostructural transition temperature. For theoretical description of the alloy properties near the magnetostructural transition a statistical model is suggested, that takes into account the coexistence of martensite and austenite domains in the vicinity of martensite transformation point.Keywords: Ferromagnetism; Magnetostructural phase transition; Magnetization; Magnetocaloric effectIn recent year Ni 2 MnGa-based ferromagnetic shape memory alloys have attracted considerable attention as a new class of actuator materials (see, for a recent review, Ref.[1]). Giant magnetocaloric effect (MCE) has also been observed in these alloys. Solid state materials with a large MCE are considered to be very perspective in creation of solid state refrigerators with high efficiency, manufacturability and ecological compatibility (Ref. [2] and references therein). In Ni-Mn-Ga alloys, the martensitic transition temperature is very sensitive to composition, which is very important for practical applications of these alloys. For instance, upon a partial substitution of Mn for Ni the martensitic transition temperature T m increases and Curie temperature T C decreases until they merge in one first-order magnetostructural phase transition (MSPT) [1]. The values of MCE in the vicinity of such a transition are likely to be maximal. The aim of our work has been to study, experimentally and theoretically, magnetic and thermodynamic properties of Ni 2.19 Mn 0.81 Ga alloy with MSPT and to determine directly the magnitude of MCE.Polycrystalline Ni 2.19 Mn 0.81 Ga alloy was prepared by a conventional arc-melting method in argon atmosphere. MCE was measured by a direct method in a calorimetric system at constant temperatures in the vicinity of MSPT. The sample for the measurement of MCE was fixed by glass wires of 10 mm in diameter glued to the sample. The change in the temperature of the sample, ∆T , with the change in magnetic field, ∆H, was measured by a differential thermocouple. A cooper screen was placed near the sample in order to decrease radiational losses. The magnetic field up to 26 kOe was created by an electromagnet.The temperature dependence of ∆T at turning the magnetic field off is presented in Fig. 1. The experimental results obtained evidence that the ∆T dependence has a peak at T ≈ 340 K. This temperature corresponds A statistical model is suggested for the theoretical description of the alloy properties near MSPT. The model takes into account coexistence of three types of martensitic and one type of austenitic structural domains in the vicinity of MSPT point [3,4]. Each structural domain is divided by 180• magnetic domains. It is postulated that the rate of transformation between structural domains is proportional to the net p...

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Magnetocaloric effect and magnetization in a Ni–Mn–Ga Heusler alloy in the vicinity of magnetostructural transition

Aliev

Batdalov

Bosko

et al. 2004

Journal of Magnetism and Magnetic Materials

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“…Some relatively old models are based on simple energy function [41,42], energy minimization [14,49,50] or using a magnetic stress to disconnect mechanical and magnetic behaviours [32,37,48]. One of the first thermodynamic approach was built in OHandley [43], O'Handley et al [44], Murray et al [40] and the addition of internal variables in the thermodynamics of irreversible processes was proposed in Hirsinger [27], Hirsinger et al [29], Creton and Hirsinger [13], Kiefer and Lagoudas [33], Kiefer et al [34] We can denote that other original approaches were studied using Preisach modeling [1], magneto-plasticity [38,39], statistical [7,21] and macroscopic with a constitutive equation [11].…”

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confidence: 99%

Magneto-thermo-mechanical modeling of a Magnetic Shape Memory Alloy Ni-Mn-Ga single crystal

Gauthier

Lexcellent

Hubert

et al. 2011

Ann. Solid Struct. Mech.

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In the frame of Thermodynamics of irreversible process, a model describing the thermomagneto-mechanical behavior of a single crystal of Ni-Mn-Ga is built. The choice of internal variables is linked to the physics of the problem (fraction of martensite variants, fraction of Weiss domains, magnetization angle). The simulations permit to describe the paths in the space (stress, temperature, magnetic field) in agreement with experimental tests. A special attention will be devoted to the control laws required to use these functional materials as sensors or actuators.

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“…This model was applied to the ferromagnetic shape memory alloys Ni-Mn-Ga in paper [3]. In contrast to paper [3] in this paper we take into account a magnetoelastic interaction in martensitic and austenitic phases as well as a dependence of relative magnetization from magnetic field.We assume that near a martensitic transition the alloy has three types of martensitic domains and one type of austenitic domain. These structural domains are divided into 180 magnetic domains.…”

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The investigations of phase transitions in Ni–Mn–Ga under external magnetic field

Bosko

Buchelnikov

Takagi

2004

Journal of Magnetism and Magnetic Materials

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The kinetics of phase transformations in ferromagnetic shape memory alloys Ni–Mn–Ga

Cited by 18 publications

References 4 publications

Magnetocaloric effect and magnetization in a Ni–Mn–Ga Heusler alloy in the vicinity of magnetostructural transition

Magnetocaloric effect and magnetization in a Ni–Mn–Ga Heusler alloy in the vicinity of magnetostructural transition

Magneto-thermo-mechanical modeling of a Magnetic Shape Memory Alloy Ni-Mn-Ga single crystal

The investigations of phase transitions in Ni–Mn–Ga under external magnetic field

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