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MA: Fachverband Magnetismus

MA 8: Magnetic Shape Memory Alloys

MA 8.14: Vortrag

Montag, 22. März 2010, 18:45–19:00, H22

Magnetic field induced strain in Ni₂MnGa-Polymer-Composites — •Sandra Weiß¹, Nils Scheerbaum¹, Jian Liu¹, Ludwig Schultz¹, Oliver Gutfleisch¹, Edith Mäder², and Gert Heinrich² — ¹IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden — ²Leibniz-Institut für Polymerforschung e.V., Hohe Straße 6, 01069 Dresden

Ni-Mn-Ga single- and polycrystals show large magnetic field induced strain (MFIS) but are in general difficult and expensive in preparation and also very brittle. An alternative to single- and polycrystals are Ni-Mn-Ga/polymer-composites. Here, small single-crystalline Ni_50.9Mn_27.1Ga_22.0-particles, produced by gently crushing melt-extracted and subsequently annealed fibres, were embedded in a soft polymer matrix. The particles have a 5M martensitic structure. The Young’s Modulus of the polymer-matrix is 2 MPa and 175 MPa, for polyurethane and epoxy respectively. In response to the applied magnetic field, the MSM particles are prone to relocation within the polyurethane due to its low Young’s modulus, leading to a very little effect of magnetic field-induced twin boundary motion. By contrast, the Ni₂MnGa-epoxy-composite shows a pronounced MFIS up to 0.1 % because the stiffness of epoxy fits better the one for Ni-Mn-Ga. Furthermore, the interface stability between Ni-Mn-Ga and epoxy-matrix was investigated by quasistatic Pull-Out Tests. First tests with silan-coupling-agent treated fibres indicate significant improvements of interface.