Martensite and nanocrystalline phase formation in rapidly solidified Ni_2MnGa alloy by melt-spinning

摘要

Microstructure of rapidly solidified Ni_2MnGa ferromagnetic shape memory alloy has been investigated experimentally by melt-spinning technique. At a constant ribbon width of 3 mm, two speeds of melt spinning 17m/sec and 30m/sec at the extrema of conditions for a good quality of ribbon resulted in two thicknesses of the ribbon, viz., 62 urn and 44 μm, respectively. TEM and AFM analysis reveals the formation of very fine clusters of Ni_2MnGa at lower wheel speeds. However at higher wheel speeds nanocrystalline Ni_2MnGa particles of size about 10-20 nm and martensitic phases were confirmed.