Effect of atomic order in Ferromagnetic Shape Memory Alloys

The contrast provided by neutron radiation for elements with similar atomic number and the possibility of using bulk samples, in which the properties induced by thermal treatments remain unchanged (which is not the case in powder samples) makes of single crystal neutron diffraction a valuable tool in fields like Ferromagnetic Shape Memory Alloys (FSMA).

FSMA have awakened a great interest in recent years for practical application in sensors and actuators due to the achievement of huge magnetic-field-induced strains (MFIS). The MFIS effect is associated with the rearrangement, under an applied magnetic field, of the crystallographic domains (twin variants) formed as a result of a thermoelastic Martensitic Transformation (MT) taking place from a high symmetry high temperature phase (austenite) to a lower symmetry low temperature phase (martensite) (Fig. 1).