The effect of rapid quenching from melt on Martensitic transition and strain cha racteristics of Ni-Mn-Ga alloy

Ni50Mn27Ga23/sub> alloy was prepared by melt_spinning at wheel velocities of 2,4 and 8m/s separately. The experimental results showed that the rapid quenching caused the decrease of the martensitic transformation temperature an d Curie temperature, while subsequent annealing would increase the depressed val ues. The NiMnGa specimens with a single_phase structure could be obtained more e asily in melt_spun ribbons than in cast alloys. Furthermore, x_ray diffraction s tudies revealed that the main diffraction peak drifted from (220) to (400) in me lt_spun ribbons, which made the texture form, and subsequent annealing made it d isappear. The effects of rapid quenching on the phase_transition strain and magn etic field_induced strain are very complicated. It was found that the phase tran sition strain and magnetic field_induced strain of melt_spun ribbons with textur e were larger than that of cast specimens.