After the observation of a shape-memory phenomenon of a Heusler-type single crystal, Ni2.18Mn0.82Ga alloy, we carried out powder neutron diffraction of this alloy by changing the temperature. Rietveld analysis of the diffraction patterns revealed that the martensitic transformation reasonably well explains the shape-memory phenomenon. It was also found that two crystal structures coexist in the martensitic phase. One is an orthorhombic structure and the other is a monoclinic structure with a shuffling of a six-layer period of the (220) plane along the  direction of this orthorhombic structure. Comparing the present results with our previous results of the powder neutron diffraction of Ni2.19Mn0.81Ga alloy under a magnetic field, where the magnetic field caused the martensitic transformation from paramagnetic mother phase to ferromagnetic martensitic phase, we can discuss the possibility of controlling the shape-memory effect by an external magnetic field.
|Journal||Applied Physics A: Materials Science and Processing|
|Publication status||Published - 2002 Dec 1|
ASJC Scopus subject areas
- Materials Science(all)