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

Ryota Kobayashi, Yoshifuru Mitsui, Rie Y. Umetsu, Kohki Takahashi, Keiichi Koyama

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish
Article number168908
JournalJournal of Magnetism and Magnetic Materials
Volume547
DOIs
Publication statusPublished - 2022 Apr 1

Keywords

  • Ferromagnetic materials
  • Heusler phases
  • High magnetic fields
  • Order-disorder phenomena
  • Phase transformation kinetics

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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