Features of Phase Composition and Structure of Rapidly Quenched Ferromagnetic Mn–Al–Ga Alloy

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Abstract

Rapidly quenched Mn55Al36Ga9 ribbons were obtained by the spinning method. In the initial quenched state, the ribbons had a two-phase structure of the ε and γ2-phases. It has been established that, upon heating, the alloy undergoes a series of phase transformations, including the precipitation of the equilibrium β-Mn phase and its subsequent dissolution, the formation of the ferromagnetic τ-phase from both the ε and γ2-phases. The largest amount of the τ-phase was obtained by annealing at a temperature of 700 °C for 20 minutes. The work describes both the phase composition obtained as a result of annealing at different temperatures and the features of the microstructure studied by electron microscopy.

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A. S. Fortuna

National Research Technological University MISiS

Author for correspondence.
Email: fortuna.as@misis.ru
Russian Federation, Moscow, 119049

T. A. Morozova

National Research Technological University MISiS

Email: fortuna.as@misis.ru
Russian Federation, Moscow, 119049

D. Yu. Karpenkov

National Research Technological University MISiS

Email: fortuna.as@misis.ru
Russian Federation, Moscow, 119049

M. V. Gorshenkov

National Research Technological University MISiS

Email: fortuna.as@misis.ru
Russian Federation, Moscow, 119049

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Supplementary files

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2. Fig. 1. X-ray diffraction spectra of tapes tempered with different linear rotation speeds of a copper wheel. The lines of the γ2 phase are marked in red, the lines of the ε phase are blue.

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3. Fig. 2. Microstructure of the quick-hardened tape (linear speed of the wheel 10 m/s): a) general appearance; b) the area of the γ2-phase; c) the area of the ε-phase; d) the area of the ε-phase with a noticeable “speckled” contrast from the ε’-phase. The corresponding electronograms are shown in the inserts for each of the regions.

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4. Fig. 3. The dependence of the heat flux on the temperature for a fast-tempered tape, obtained by differential scanning calorimetry. The sample was heated and cooled twice.

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5. Fig. 4. X-ray diffraction spectra of hardened and annealed tapes at different temperatures (annealing duration 20 min). Approximating spectra obtained by the Rietveld method are superimposed on the experimental spectra. The lines of the γ2-phase are marked in red, the lines of the ε-phase are blue, the τ-phases are black, (β-Mn) are green.

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6. Fig. 5. The dependences of the volume fractions of the phases contained in the quick-quenched tape, depending on the annealing temperature.

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7. Fig. 6. Microstructure of a quick-tempered tape annealed at 440 °C for 20 minutes. The image is obtained in the signal of reflected electrons.

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8. Fig. 7. Microstructure of the t-phase of the tape annealed at 700 °C for 20 min: light-field (000) (a) and dark-field (001) (c), (002) (d), (110) (e) images, image designations correspond to reflexes on the electronogram (b).

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