Properties of Co-alloyed Ni-Fe-Ga ferromagnetic shape memory alloys

It is experimentally found that in the Ni54Fe20-xCoxGa26 ferromagnetic shape memory alloys, Co variation from 0 to 9 at.% leads to: (i) almost linear change of martensitic transformation temperatures from 270 °C to 120 °C; (ii) a non-monotonous change of the Curie temperature, and (iii) a linear decrease of saturation magnetization from 60 to 43 Am2/kg. The selected alloys grown as single crystals have been (magneto-)mechanically tested. The superelastic effect has been measured to be about 4%. The magneto-strain shows a training effect which is an evidence of the effect of magnetic-field-induced twin-boundary motion.