Diffusionless nature of D0 3  → L1 2 transition in Fe 3 Ga alloys

Golovin, I.S.; Palacheva, V.V.; Базлов, А. И.; Cifré, J.; Nollmann, Niklas; Divinski, Sergiy V.; Wilde, Gerhard

doi:10.1016/j.jallcom.2015.10.041

Cited by 36 publications

(9 citation statements)

References 25 publications

(32 reference statements)

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“…1a clearly show that the first magnetization drop at ∼700 K corresponds to the Curie transition of DO 3 phase27, where the net magnetization reduces by over 80 % when compared with that at 300 K, indicating that the DO 3 phase has a relatively large volume fraction. The following changes are consistent with the equilibrium phase diagram19, which are the bcc→L1 2 and ferromagnetic L1 2 →paramagnetic DO 19 transformations, respectively272833. Evidence for the bcc→L1 2 transformation is presented by the blue curve in the X-ray diffraction data in Fig.…”

Section: Resultssupporting

confidence: 78%

“…Since the discovery in 2000, mechanically strong and malleable Fe 100− x Ga x alloys (known as Galfenol) have attracted intensive attention due to the combination of large magnetostriction, low switching field and high T C , which are promising for applications in sensors, actuators and transducers1213141516171819202122232425262728. Previous investigations182021222324 have shown that both magnetization and structure of the Fe 100− x Ga x alloys are very sensitive to heat treatments.…”

mentioning

confidence: 99%

“…Among these phases, L1 2 possesses the largest magnetization. Formation of the L1 2 phase is usually based on a kinetically slow diffusion transformation from bcc precursors262728, for instance, long-term aging (3 days annealing at 773 K followed by 1 month at 623 K (ref. 21)) or slow cooling (at 0.1 K min −1 (ref.…”

mentioning

confidence: 99%

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Highly thermal-stable ferromagnetism by a natural composite

Ma¹,

Gou²,

Hu³

et al. 2017

Nat Commun

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All ferromagnetic materials show deterioration of magnetism-related properties such as magnetization and magnetostriction with increasing temperature, as the result of gradual loss of magnetic order with approaching Curie temperature TC. However, technologically, it is highly desired to find a magnetic material that can resist such magnetism deterioration and maintain stable magnetism up to its TC, but this seems against the conventional wisdom about ferromagnetism. Here we show that a Fe–Ga alloy exhibits highly thermal-stable magnetization up to the vicinity of its TC, 880 K. Also, the magnetostriction shows nearly no deterioration over a very wide temperature range. Such unusual behaviour stems from dual-magnetic-phase nature of this alloy, in which a gradual structural-magnetic transformation occurs between two magnetic phases so that the magnetism deterioration is compensated by the growth of the ferromagnetic phase with larger magnetization. Our finding may help to develop highly thermal-stable ferromagnetic and magnetostrictive materials.

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Section: Resultssupporting

confidence: 78%

mentioning

confidence: 99%

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Highly thermal-stable ferromagnetism by a natural composite

Ma¹,

Gou²,

Hu³

et al. 2017

Nat Commun

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“…This effect relates to a complex phase transformation sequences in the Fe-27%Ga alloys. Phase transitions in Fe 3 Ga-type alloys were first studied by X-ray diffraction [3][4][5] , and more recently by in situ neutron diffraction 2,6,7 to characterize the bulk alloy. Different ratios between metastable and equilibrium phases characterized by magnetostriction values of different signs vary the magnetostriction values of the alloy, λ S , from positive to negative, including the value of λ S = 0 2 .…”

Section: Introductionmentioning

confidence: 99%

Anelasticity of Phase Transitions and Magnetostriction in Fe-(27-28%)Ga Alloys

et al. 2018

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Several aspects of anelastic behavior of Fe-(27-28%)Ga-Tb alloys are considered in this paper: (i) the phase transitions from a metastable to an equilibrium phase and phase transitions between equilibrium phases at higher temperatures in as cast alloys, (ii) the nature of corresponding three transient anelastic effects, (iii) the formation of an intrinsic composite microstructure with a different ratio between the bcc-derivative metastable and fcc-derivative equilibrium phases that have different magnetostriction and the effect of alloys doping by Tb to stabilize the metastable phase with high positive values of magnetostriction.

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“…Проведено исследование кинетики формирования равновесной структуры при отжиге. Режимы изотермического отжига были выбраны на основе ранее проведенных исследований фазовых превращений в этих сплавах при нагреве методом in situ дифракции нейтронов [20,21] и рентгеновских лучей [22,23]. Для структурных исследований был выбран интервал температур изотермического отжига от 400 до 500°С, который позволяет надежно варьировать и контролировать структуру сплавов.…”

Section: влияние отжига на структуруunclassified

The influence of microalloying and heat treatment on the structure and properties of Galfenol with high gallium concentration

Palacheva¹,

Чеверикин²,

Zanaeva³

et al. 2019

LOM

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The structure of soft-magnetic and magnetostrictive alloys of the Galfenol type Fe-(27-28) at.% Ga after various heat treatment regimes has been studied. The features of formation of both metastable and equilibrium ordered phases in alloys based on Fe-Ga and Fe-Ga-rare-earth elements have been examined. Alloys of these systems belong to the class of highly magnetostrictive materials (up to 400 ppm for monocrystals) used in electromagnetic drives and special sensors. Two-phase alloys with a nonequilibrium phase based on the bcc lattice (D0 3 structure) and the equilibrium phase based on the fcc lattice (L1 2 structure) are investigated. Isothermal annealing of the Fe 3 Ga alloy at 400°C was used to obtain a microstructure that allows analysis of the kinetics of phase transformations under well-controlled conditions. It is established that isothermal annealing entails the formation of a microstructure with a certain ratio of metastable bcc and equilibrium fcc phases having different magnetic properties. The kinetics and mechanisms of phase transformations in binary Fe-Ga alloys and in multicomponent Fe-Ga-Tb alloys are systematically studied using a complex of methods of physical material science (X-ray diffraction (XRD), scanning electron microscopy with EBSD analysis (SEM-EBSD), optical microscopy (LM), vibration magnetometer (VSM), mössbauer spectroscopy. The influence of microalloying of the alloys with terbium on structure and functional characteristics is discussed. The role of Tb in the stabilization of nonequilibrium phases at room temperature is shown. The influence of small additions (0.5 at.%) of Tb on the changes in the structure Fe-Ga alloys was studied by mössbauer spectroscopy.

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Diffusionless nature of D0 3 → L1 2 transition in Fe 3 Ga alloys

Cited by 36 publications

References 25 publications

Highly thermal-stable ferromagnetism by a natural composite

Highly thermal-stable ferromagnetism by a natural composite

Anelasticity of Phase Transitions and Magnetostriction in Fe-(27-28%)Ga Alloys

The influence of microalloying and heat treatment on the structure and properties of Galfenol with high gallium concentration

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