Development of Multi-Function Heusler Type Ferromagnetic Shape Memory Alloy

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The final aim of this project is to make the materials of ferromagnetic shape memory alloy. Multifunctional Heusler-type ferromagnetic shape memory alloy, NiィイD22ィエD2MnGa, has been developed. Arc-melt materials, SPS materials and sputtered films of NiィイD22ィエD2MnGa were made and these physical and material properties were measured.1. Physical properties of arc melted bulk material : NiィイD22ィエD2MnGa added by Fe or Co were made and these phase transformation and Curie temperatures were measured. These temperatures changed by Fe or Co addition. These phenomena were discussed by the electron/atom ratio. The effect of magnetic field on the transformation temperatures was studied. Pre-martensitic transformation temperature decreased and martensitic transformation temperature increased with increase of magnetic field of 0〜2T. They became constant over 2T to 5T.2. Fabrication by sintering method and physical properties : Spark Plasma Sintering (SPS) method which is one of powder metallurgy meth … More ods was applied in order to make flexible specimen. Powder specimens were mad from an arc-melted ingot. Crystal structure and transformation temperatures were measured and they were almost same as the bulk specimen. The Young's modulus was measured above and below transformation temperatures in order to study the mechanical properties of this material. This SPS material had about 1% strain by elongation and the brittleness of this materials was improved compared to the bulk specimen.3. Fabrication of sputtered film and physical properties, shape memory effect : Sputtered film with 5μm in thickness was deposited on a polyvinyl alcohol (PVA) substrate using a high frequency magnetron sputtering apparatus by control of the high frequency power and the target. After removing from a PVA substrate, the film which had smaller brittleness was annealed. Crystal structure and transformation temperatures were measured and they were almost same as the bulk specimen. The magnetic properties measured and they had unique temperature dependence of film. The flat shape of this film bent to right angle and then this shape changed to original flat shape by heating. This phenomena shows the one way shape memory effect. This ferromagnetic shape memory film will be used to micro-actuator for micro-machine. Less