Undercooling growth and magnetic characterization of ferromagnetic shape memory alloy Ni2FeGa single crystals

Ni2FeGa single crystals have been grown in undercooling conditions provided by a glass-purification method. It has been found that trace amounts of gamma phase embededin the single crystalline matrix preferentially orients in the <100> orientation along the growth direction. This gamma phase generates directional residual stress and results in an anisotropic two-way shape memory effect. Large strains of -2.5% in the [001] and 1.5% in the [010] directions have been observed. This trace gamma phase also improves the ductility of the material and thus the crystals could be plastically deformed at room temperature in the parent phase. The <110> and <111> orientations in Ni2FeGa alloy were identified as the easy and hard magnetization directions, respectively, in the parent phase by using low field M-T measurements.