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

Ni50Mn27Ga23 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 and Curie temperature, while subsequent annealing would increase the depressed values. The NiMnGa specimens with a single-phase structure could be obtained more easily in melt-spun ribbons than in cast alloys. Furthermore, x-ray diffraction studies revealed that the main diffraction peak drifted from (220) to (400) in melt-spun ribbons, which made the texture form, and subsequent annealing made it disappear. The effects of rapid quenching on the phase-transition strain and magnetic field-induced strain are very complicated. It was found that the phase transition strain and magnetic field-induced strain of melt-spun ribbons with texture were larger than that of cast specimens.