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

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.

Keywords:
Fe-Ga; mechanical spectroscopy; transient effects; magnetostriction; neutron diffraction; phase transitions

Authorship

Igor Stanislavovich Golovin ^**e-mail: i.golovin@misis.ru

National University of Science and Technology MISiS, Moscow, RussiaNational University of Science and Technology MISiSRussiaMoscow, RussiaNational University of Science and Technology MISiS, Moscow, Russia

http://orcid.org/0000-0002-9923-4629

Valeria Valerievna Palacheva

Aliakbar Emdadi

Daniele Mari

Ecole Polytechnique Fédérale de Lausanne, Lausanne, SuisseEcole Polytechnique Fédérale de LausanneSwitzerlandDubna, SwitzerlandEcole Polytechnique Fédérale de Lausanne, Lausanne, Suisse

http://orcid.org/0000-0003-2075-9463

Alexei Heintz

Ecole Polytechnique Fédérale de Lausanne, Lausanne, SuisseEcole Polytechnique Fédérale de LausanneSwitzerlandDubna, SwitzerlandEcole Polytechnique Fédérale de Lausanne, Lausanne, Suisse

Аnatoliy Mikhailovich Balagurov

Joint Institute for Nuclear Research, Dubna, RussiaJoint Institute for Nuclear ResearchRussiaDubna, RussiaJoint Institute for Nuclear Research, Dubna, Russia

Ivan Anatolievich Bobrikov

Joint Institute for Nuclear Research, Dubna, RussiaJoint Institute for Nuclear ResearchRussiaDubna, RussiaJoint Institute for Nuclear Research, Dubna, Russia

*e-mail: i.golovin@misis.ru

SCIMAGO INSTITUTIONS RANKINGS

Ecole Polytechnique Fédérale de Lausanne, Lausanne, SuisseEcole Polytechnique Fédérale de LausanneSwitzerlandDubna, SwitzerlandEcole Polytechnique Fédérale de Lausanne, Lausanne, Suisse

Joint Institute for Nuclear Research, Dubna, RussiaJoint Institute for Nuclear ResearchRussiaDubna, RussiaJoint Institute for Nuclear Research, Dubna, Russia

Figures | Formulas

Figures (7)
Formulas (1)

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Figure 1
TDIF curves measured at heating with 1 K/min rate using bending (up to 600°C, DMA Q800; left figure) and torsion (up to 800°C, inverted pendulum; right figure) vibrations with different frequencies from 0.02 to 30 Hz (see in figures).

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Figure 2
Phase transitions in the Fe-27.0Ga (a) samples heated with a rate of 2 K/min obtained by normalizing the intensities of the characteristic diffraction peaks at their maximum values (reduction of the A2 phase above 700°C is associated with a gradual decrease in the intensity of the magnetic contribution to the peaks); (b) First derivatives of the above curves-the rate of the phase transitions-illustrate the rate of growth and the dissolution of different phases. (c) Atomic volumes of the phases in the same temperature range.

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Figure 3
a) The Tr1-peak height as a function of inverse frequency for three different heating rates; b) TDIF curve with interrupted heating at 470°C. Inset: The decrease of the Tr1 peak as a function of time of isothermal annealing (green circles) and intensities of neutron diffraction lines from decaying D0₃ phase (blue down triangles) and growing L1₂ phase (red up triangles) under the same conditions.

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Figure 4
Magnetostriction vs applied field and different dispersion of the L1₂ (red color) phase at 400 (fine) and 475/500°C (coarse grains).

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Figure 5
Topography (a), low magnification MFM (b), and high magnification MFM (c) images of the Fe-27.8Ga sample annealed at 400 °C for 600 min showing D0₃ (darker contrast) and L1₂ (brighter contrast) phases.

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Figure 6
Second and third transition peaks in the Fe-27.8Ga sample: a) influence of the frequency of vibrations (from 0.05 to 1 Hz, heating rate 1 K/min), b) influence of the heating rate (from 0.5 to 3 K/min, 1 Hz).

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Figure 7
(a) Amount of L1₂ phase determined by X-ray analysis after isothermal annealing in the Fe-27.4Ga (yellow circles) and in the Fe-27.4Ga-0.5Tb (red circles) samples; (b) Phase transitions in the Fe-27.4Ga-0.3Tb sample according to the in situ neutron diffraction (Intersity, left Y-axe) and TDIF (black curve corresponds to right Y-axe).

Thumbnail

(1)

Figure 1 TDIF curves measured at heating with 1 K/min rate using bending (up to 600°C, DMA Q800; left figure) and torsion (up to 800°C, inverted pendulum; right figure) vibrations with different frequencies from 0.02 to 30 Hz (see in figures).

Figure 2 Phase transitions in the Fe-27.0Ga (a) samples heated with a rate of 2 K/min obtained by normalizing the intensities of the characteristic diffraction peaks at their maximum values (reduction of the A2 phase above 700°C is associated with a gradual decrease in the intensity of the magnetic contribution to the peaks); (b) First derivatives of the above curves-the rate of the phase transitions-illustrate the rate of growth and the dissolution of different phases. (c) Atomic volumes of the phases in the same temperature range.

Figure 3 a) The Tr1-peak height as a function of inverse frequency for three different heating rates; b) TDIF curve with interrupted heating at 470°C. Inset: The decrease of the Tr1 peak as a function of time of isothermal annealing (green circles) and intensities of neutron diffraction lines from decaying D0₃ phase (blue down triangles) and growing L1₂ phase (red up triangles) under the same conditions.

Figure 4 Magnetostriction vs applied field and different dispersion of the L1₂ (red color) phase at 400 (fine) and 475/500°C (coarse grains).

Figure 5 Topography (a), low magnification MFM (b), and high magnification MFM (c) images of the Fe-27.8Ga sample annealed at 400 °C for 600 min showing D0₃ (darker contrast) and L1₂ (brighter contrast) phases.

Figure 6 Second and third transition peaks in the Fe-27.8Ga sample: a) influence of the frequency of vibrations (from 0.05 to 1 Hz, heating rate 1 K/min), b) influence of the heating rate (from 0.5 to 3 K/min, 1 Hz).

Figure 7 (a) Amount of L1₂ phase determined by X-ray analysis after isothermal annealing in the Fe-27.4Ga (yellow circles) and in the Fe-27.4Ga-0.5Tb (red circles) samples; (b) Phase transitions in the Fe-27.4Ga-0.3Tb sample according to the in situ neutron diffraction (Intersity, left Y-axe) and TDIF (black curve corresponds to right Y-axe).

(1)

Q_{Tr}^{- 1} = \frac{k}{J} \frac{dn}{dT} \frac{T}{ω^{m}},

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

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[1] *e-mail: i.golovin@misis.ru