Effect of temperature on magnetic properties of Ni-Mn-Ga magnetic shape memory (MSM) alloys

Author

Heczko, Oleg ; Ullakko, Kari

Author_Institution

Dept. of Eng. Phys. & Math., Helsinki Univ. of Technol., Espoo, Finland

Volume

37

Issue

4

fYear

2001

fDate

7/1/2001 12:00:00 AM

Firstpage

2672

Lastpage

2674

Abstract

Single crystal Ni₄₈Mn₃₁Ga₂₁ magnetic shape memory alloy exhibits giant 5% field-induced strain (MSM effect) due to redistribution of martensitic variants. Magnetization of this alloy was studied as a function of field and temperature. Austenite-to-martensite transition occurs at 299 K. At room temperature the magnetization loop of the martensitic sample exhibits large transient hysteresis in the first quadrant, which is a direct manifestation of the MSM effect. When cooling from room temperature, the observed changes of magnetization curves suggest that the large MSM effect strongly decreases with temperature and about 50 deg. below the martensitic transformation vanishes entirely. The disappearance is mostly due to decreasing mobility of the martensitic twin boundaries. At 210 K, an additional intermartensitic transition occurs which results in a new phase with low magnetic anisotropy

Keywords

ferromagnetic materials; gallium alloys; magnetic anisotropy; magnetic hysteresis; magnetisation; magnetoelastic effects; manganese alloys; martensitic transformations; nickel alloys; shape memory effects; twin boundaries; Ni₄₈Mn₃₁Ga₂₁; Ni₄₈Mn₃₁Ga₂₁ single crystal; austenite-martensite transition; intermartensitic transition; magnetic anisotropy; magnetic field induced strain; magnetic properties; magnetic shape memory alloy; magnetization; magnetoelastic deformation; temperature effect; transient hysteresis; twin boundary; Biomedical measurements; Lattices; Magnetic anisotropy; Magnetic field induced strain; Magnetic field measurement; Magnetic properties; Magnetization; Perpendicular magnetic anisotropy; Shape memory alloys; Temperature dependence;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.951270

Filename

951270