Abstract
The martensitic transformation and magnetic properties of ferromagnetic shape memory alloy Ni50+xFe25-xGa25 (x=-1, 0, 1, 2, 3, 4) ribbons have been systematically studied. It has been found that with the increase of Ni concentration, the martensitic transformation temperature increases, but the Curie temperature decreases. Both the two-step thermally induced structural transformation and the one-step transition have been observed in NiFeGa alloys with different compositions. It is found that the two-step transition became the one-step transition after the ribbon being heat treated at 873 K or higher. X-ray diffraction patterns show that only L21→B2 transition occurs in the samples treated at 873 K, while the γ phase will form in the samples treated at higher temperature. Transmission electron microscopy (TEM) studies show that the alloys with martensitic transformation temperature above the room temperature are non-modulated martensite with the large domain size, being different from the stoichiometric Ni2FeGa alloy that is a modulated martensite with small domain size. The influences of Fe substitution for Ni in Ni2FeGa on the saturation magnetization and exchange interaction are also discussed.
Original language | English (US) |
---|---|
Pages (from-to) | 214-220 |
Number of pages | 7 |
Journal | Physics Letters, Section A: General, Atomic and Solid State Physics |
Volume | 329 |
Issue number | 3 |
DOIs | |
State | Published - Aug 23 2004 |
Externally published | Yes |
Keywords
- Heusler alloy
- Magnetism
- Martensitic transformation
ASJC Scopus subject areas
- General Physics and Astronomy