Title :
Structure and phase transformation of ferromagnetic shape memory alloy Ni49Mn30Ga21 fine particles prepared by spark erosion
Author :
Tang, Y.J. ; Smith, David.J. ; Hu, Hao ; Spada, F.E. ; Harper, H. ; Berkowitz, A.E.
Author_Institution :
Phys. Dept., Univ. of California, La Jolla, CA, USA
Abstract :
Ni49Mn30Ga21 fine particles were prepared by spark erosion. Most of the particles are spheres with sizes ranging from about 5 nm to 100 μm. The particles have martensite structure at room temperature as indicated by X-ray diffraction (XRD). Measurements of the temperature dependence of the magnetization and high-temperature XRD patterns demonstrated that the particles undergo a martensite → austenite phase transformation in the range 35°C-70°C during heating, with ∼10°C hysteresis for the austenite → martensite transformation upon cooling.
Keywords :
X-ray diffraction; ferromagnetic materials; gallium alloys; magnetic particles; magnetisation; manganese alloys; martensitic transformations; nanoparticles; nickel alloys; particle size; reverse martensitic transformations; shape memory effects; 35 to 70 degC; 5 nm to 100 micron; Ni49Mn30Ga21; Ni49Mn30Ga21 fine particles; X-ray diffraction; austenite-martensite transformation; cooling; ferromagnetic shape memory alloy; heating; high-temperature XRD patterns; hysteresis; magnetization; martensite structure; martensite-austenite phase transformation; phase transformation; room temperature; spark erosion; spheres; structure; temperature dependence; Heating; Magnetization; Particle measurements; Phase measurement; Shape memory alloys; Sparks; Temperature dependence; Temperature measurement; X-ray diffraction; X-ray scattering;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2003.816165
