Influence of thermal treatment on local structure and magnetic properties of NiMnGa alloys

Summary form only given. Nearly stoichiometric Ni/sub 2/MnGa alloys with martensitic structure exhibit a magnetic shape memory (MSM) effect caused by activation of twin boundary motion in magnetic field. The field-induced reorientation of martensite can cause more than 4% length variation. The effect strongly depends on alloys composition and structure. Due to the complex structure of martensitic phase the interpretation of the results obtained by x-ray diffraction is ambiguous. Moreover optimum MSM effect could be expected for metastable state. Thus the microstructure of the alloys should be controlled.