The magnetic controllability of the thermoelastic martensitic transformation, which is the origin of the shape-memory effect, has been investigated. We have carried out neutron diffraction measurements of a Heusler-type off-stoichiometric Ni2.19Mn0.81 Ga alloy under the magnetic field of up to 5 T using the HERMES and the TAS-2 diffractometers both installed at the JRR-3M reactor of Japan Atomic Energy Research Institute (JAERI). This alloy has the martensitic transformation temperature (MS point) of about 350 K, which coincides with the magnetic Curie temperature (TC). It is ferromagnetic in the martensitic phase and paramagnetic in the cubic Heusler phase. By Rietveld analysis of the diffraction patterns we have confirmed that the martensitic phase and the cubic phase coexist at 350 K. We have also discovered that half of the cubic phase changes to martensitic phase under the magnetic field of 5 T at this temperature. This finding indicates the possibility of controlling the martensitic transformation by means of the external magnetic field.
- Magnetic field induced martensitic transformation
- Neutron diffraction
- NiMnGa-based alloys
ASJC Scopus subject areas
- Physics and Astronomy(all)