Effect of external stress and bias magnetic field on transformation strain of heusler alloy Ni-Mn-Ga

The influence of external field(magnetic field and stress field) on the transformation strain of Ni 52.9- Mn 24.4Ga 22.7 single crystal were investigated and its mechanism was also discussed. When thermally martensitic transformation occurs, about 0.25% transformation strain is obtained which may be obviously enhanced to about 0.8% by a 6 000 Oe magnetic bias field. However, the strain decreases by the external compress stress loaded along the strain-measured direction. When the external compress stress and bias magnetic field are simultaneously applied, the transformation strain decreases with increasing the magnetic field, which is related to the rearrangement of the martensite variants influenced by the external field.