1015 Fabrication and characterization in ferromagnetic NiMnGa shape memory alloy/polymer composite
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Ferromagnetic shape memory alloys (FSMAs) can have larger strain and more quick response than presently-used actuator materials. In FSMAs, the magnetic field-induced strains (MFISs) result from rearrangement of martensitic variants by magnetic field. Several research groups have reported large MFISs〜10% in some nonstoichiometric NiMnGa "single crystals". However, they are essentially irrecoverable upon removal of the field. In our laboratory, NiMnGa/polymer composites are proposed for recoverable MFISs. Polycrystalline NiMnGa was crushed into particles and they were embedded in a polymer matrix. The particles are essentially single crystals. In the present study, rearrangement of twin variants under externally applied fields were observed in embedded particles.
