Regensburg 2004 – scientific programme

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MA: Magnetismus

MA 24: Symposium Magnetic Shape Memory Alloys (zusammen mit M)

MA 24.2: Talk

Thursday, March 11, 2004, 12:00–12:15, H23

Influence of composition and heat treatment on structure and magnetic properties of NiMnGa shape memory alloys — •Stefan Roth¹, Norbert Mattern¹, and Andrea Böhm² — ¹IFW Dresden, POB 270116, D-01171 Dresden — ²FhG IWU, Bamberger Strasse 7, D-01187 Dresden

Ferromagnetic Ni(100-x-y)Mn(x)Ga(y) - alloys were prepared by arc melting pure constituents with (x,y) = (26,22) and (29 or 30, 20 or 21). The Curie temperature and the martensitic transformation temperature were determined by a Faraday magnetometer and differential scanning calorimetry, respectively. Magnetisation as a function of field and temperature was measured by a vibrating sample magnetometer and the crystalline structure was investigated using XRD. The magnetic anisotopy field was derived from the field dependence of the magnetisation. Annealing above the order temperature and cooling at different rates causes changes in the magnetic properties and the transformation behaviour which are correlated to changes in the degree of order, changes in the lattice parameters and in the amount of remaining austenite.