Phase diagram and magnetic moment of Ni50+xMn 27-xGa23 ferromagnetic shape memory alloys

R. Y. Umetsu, H. Ando, S. Yamashita, K. Endo, H. Nishihara, R. Kainuma, T. Kanomata, K. R.A. Ziebeck

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Permeability, magnetization, differential scanning calorimetry and X-ray powder diffraction measurements were carried out on the off-stoichiometric ferromagnetic shape memory alloys Ni50+xMn27-xGa 23 (-25 ≤ x ≤ 6) in order to establish the phase diagram over a wide range of concentration. The phase diagram was found to comprise of four regions, a paramagnetic austenite phase (Para-A), a paramagnetic martensite phase (Para-M), a ferromagnetic austenite phase (Ferro-A) and a ferromagnetic martensite phase (Ferro-M). Furthermore the martensitic transformation and the Curie temperatures crossed over at around x = 2.5. The martensitic transformation was found to occur over a wide Mn-rich region. A linear increase in the martensitic transformation temperature with increasing number of valence electrons per atom, e/a, was limited to a narrow concentration range around x = 0.0. Overall the martensitic transformation temperature exhibited a concave behavior with a minimum occurring at approximately x = -8.

Original languageEnglish
Pages (from-to)521-528
Number of pages8
JournalJournal of Alloys and Compounds
Volume579
DOIs
Publication statusPublished - 2013 Jan 1

Keywords

  • Magnetic moment
  • Magnetically ordered materials
  • Martensitic transformation temperature
  • Ni-based Heusler alloy
  • Phase diagram
  • The Curie temperature

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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