Development of NiMnGa-based ferromagnetic shape memory alloy by rapid solidification route

The ferromagnetic shape memory alloy with nominal composition of Ni_52.5Mn_24.5Ga₂₃(at%) was developed by the melt-spinning technique. The as-spun ribbon showed dominant L2₁ austenitic (cubic) structure with splitting of primary peak in the X-ray diffractogram indicating existence of a martensitic feature. The quenched-in martensitic plates were revealed from Transmission electron microscopy (TEM). Increase of magnetisation at low-temperature rise indicates martensite to austenite transformation and its reverse with a drop in magnetisation during cooling cycle. The martensite to austenite transformation can be made spontaneous at higher magnetic field.