Phase-structural state of τ-MnAl(Ga) alloys prepared at different cooling rates

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Abstract

An alloy with a nominal composition of Mn55Al36Ga9 is prepared by four different methods which ensure different cooling rates. Two bulk samples are prepared by induction melting followed by water quenching from a homogenizing temperature of 1100oС; one of the samples was sealed in a quartz ampoule and subjected to water quenching, whereas the other sample directly was subjected to water quenching. Two samples are prepared in the form of ribbons by quenching from the melt on a rotating copper wheel at linear speeds of 10 and 40 m/s. Thus, samples quenched at different rates are prepared. For these samples, regularities of phase transitions occurred during heating are determined, and difference in the regularities for the bulk and rapidly quenched samples are found. Based on the data obtained, we make an assumption that the γ2 → τ phase transition has features of a bulk transition. Magnetic hysteretic properties of the rapidly quenched ribbons are measured. The high thermal stability of the rapidly quenched ribbons alloyed with gallium is shown.

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About the authors

A. S. Fortuna

National University of Science and Technology MISiS

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

N. M. Vazhinskii

National University of Science and Technology MISiS

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

K. S. Nechaev

National University of Science and Technology MISiS

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

T. A. Morozova

National University of Science and Technology MISiS

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

M. V. Gorshenkov

National University of Science and Technology MISiS

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

D. Y. Karpenkov

National University of Science and Technology MISiS

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

E. S. Malyutina

National University of Science and Technology 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 patterns of samples quenched (a) in water (1 – quenching, 2 – annealing at 500°C, 3 – annealing at 700°C, thin black line – approximation); (b) with an ampoule (1 – quenching, 2 – annealing at 700°C, thin black line – approximation).

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3. Fig. 2. Dependences of heat flow on temperature during heating and cooling for massive samples obtained: a) by quenching with an ampoule, b) by quenching in water; solid line – heating, dashed line – cooling.

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4. Fig. 3. Microstructure of massive samples after: a) quenching in water, b) quenching in water and annealing at 500°C, c) quenching in water and annealing at 700°C, d) quenching with an ampoule, d) quenching with an ampoule and annealing at 500°C, e) quenching with an ampoule and annealing at 700°C.

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5. Fig. 4. Microstructure of the original rapidly quenched tapes, quenched at the linear speed of rotation of the copper wheel: a – 10 m/s, b – 40 m/s.

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6. Fig. 5. Dependencies of heat flow during the first and repeated heating of rapidly quenched tapes.

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7. Fig. 6. X-ray diffraction patterns of a tape hardened at a linear wheel speed of 40 m/s in the initial – 1, and annealed at different temperatures states: 2 – 400°C, 3 – 550°C, 4 – 650°C, 5 – 700°C, thin line – approximation.

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8. Fig. 7. Dependences of the volume fractions of phases of tapes rapidly quenched at v = 10 m/s and at v = 40 m/s on the annealing temperature.

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9. Fig. 8. Hysteresis loops for tapes obtained at a copper wheel rotation speed of 10 and 40 m/s.

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10. Fig. 9. X-ray diffraction patterns of tapes rapidly quenched at v = 10 m/s, annealed at 700°C for different periods of time.

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