Modification in martensite morphology and magneto-strain through rapid solidification and heat treatment of NiMnGaAl alloy

The influence of melt spinning and heat treatment on the structure, phase transformation and magnetic field induced strain (MFIS) properties have been investigated for Ni55Mn22Ga22Al1 (at%) alloy. The microstructure showed distinct improvement in morphology of as spun ribbon as compared to ingot. Annealing further enhanced martensite state and displayed systematic arrangement of dislocations. It contributed to increase MFIS to 482 ppm in annealed ribbon as compared to 190 ppm and 28 ppm for as-spun ribbon and ingot, respectively.