Regensburg 2007 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 17: Magnetic Shape Memory Alloys

MA 17.14: Vortrag

Mittwoch, 28. März 2007, 18:30–18:45, H10

Martensitic transformation and magnetic properties of Ni-Fe-Ga-Co magnetic shape memory alloys — •Jian Liu, Nils Scheerbaum, Dietrich Hinz, and Oliver Gutfleisch — IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden, Germany

To overcome the disadvantage of brittleness in Ni-Mn-Ga alloys, Ni-Fe-Ga-Co alloys with a Ga content of 27 at.% were reported as a new magnetic shape memory (MSM) system due to its good ductility, high mobility of twin boundaries and high martensitic transformation temperature Tm as well as magnetic transition temperature Tc [1]. In this work, the effects of substitution of Co for Ni on the martensitic and magnetic properties in Ni-Ga-Fe alloys with a wider composition range were studied. The influence of composition on the crystal structure of martensite phase was also presented. A series of polycrystalline alloys, Ni54-xFe20Ga26Cox, Ni54-xFe19Ga27Cox and Ni54-xFe18Ga28Cox (x = 0, 2, 4, 6) was produced using arc-melting. As-cast samples were homogenized at 1453 K to obtain a single-phase structure followed by annealing at 673 K to achieve a high degree of atomic order. Tm was measured by differential scanning calorimetry (DSC). Tc and magnetisation were determined by vibrating sample magnetometer (VSM). The structure was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that Tm and Tc can be tailored by adjusting the composition of the Ni-Fe-Ga-Co alloys.

[1] Morito, K. Oikawa, A. Fujita, K. Fukamichi, R. Kainuma, K. Ishida, T. Takagi, J. Mag. Mag. Mater. 290-291 (2005) 850.