Acceleration of B2/L21 order-disorder transformation in Ni2MnAl Heusler alloys by in-magnetic-field annealing

•In-field heat treatment for B2-Ni2MnAl at 673 K was carried out at 15 T.•Phase formation of ferromagnetic L21 phase was accelerated by magnetic field.•Order-disorder transformation behavior was analyzed by Johnson-Mehl-Avrami equation.•Phase formation of L21 phase at 15 T was over 5 times faster th...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 2022-04, Vol.547, p.168908, Article 168908
Main Authors: Kobayashi, Ryota, Mitsui, Yoshifuru, Umetsu, Rie Y., Takahashi, Kohki, Koyama, Keiichi
Format: Article
Language:English
Subjects:
Annealing
Antiferromagnetism
Avrami equation
Ferromagnetic materials
Ferromagnetism
Heusler alloys
Heusler phases
High magnetic fields
Magnetic fields
Magnetism
Order-disorder phenomena
Order-disorder transformations
Phase transformation kinetics
Transformation temperature
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Summary:•In-field heat treatment for B2-Ni2MnAl at 673 K was carried out at 15 T.•Phase formation of ferromagnetic L21 phase was accelerated by magnetic field.•Order-disorder transformation behavior was analyzed by Johnson-Mehl-Avrami equation.•Phase formation of L21 phase at 15 T was over 5 times faster than that in a zero field. Ferromagnetic L21 phase of Ni2MnAl with high order degree is difficult to synthesize because of low L21/B2 order-disorder transformation temperature. It is found that magnetic field accelerated the transformation from the antiferromagnetic disordered B2 to ordered L21 phase. Magnetization increased by in-magnetic-field annealing at 673 K, which indicated the acceleration of the ordering to L21 phase. Magnetic field effects on the B2/L21 order-disorder transformation were discussed based on magnetic-field-induced change of transformation temperature, enhancement of degree of order at annealing temperature, and reduction of critical radius of L21 nuclei. Growth kinetics of L21 phase were evaluated by Johnson-Mehl-Avrami equation, which indicated that 15-T annealing accelerated the growth of L21 phase 5.7 times faster than zero-field annealing. Our results showed that magnetic field can contribute to shortening the annealing time for synthesis of ferromagnetic L21-Ni2MnAl alloy.
ISSN:0304-8853
1873-4766
DOI:10.1016/j.jmmm.2021.168908