Entropy change at the martensitic transformation in ferromagnetic shape memory alloys Ni_{2+x}Mn_{1-x}Ga

Abstract

The entropy change $\Delta S$ between the high-temperature cubic phase and the low-temperature tetragonally-based martensitic phase of Ni${}_{2+x}$Mn${}_{1-x}$Ga ($x=0-0.20$) alloys was studied. The experimental results obtained indicate that $\Delta S$ in the Ni${}_{2+x}$Mn${}_{1-x}$Ga alloys increases with the Ni excess $x$. The increase of $\Delta S$ is presumably accounted for by an increase of magnetic contribution to the entropy change. It is suggested that the change in modulation of the martensitic phase of Ni${}_{2+x}$Mn${}_{1-x}$Ga results in discontinuity of the composition dependence of $\Delta S$.

presented at MMM-47, to be published in J. Appl. Phys. (May 15, 2003)

References in corpus (1)

• Magnetic properties of Ni2.18Mn0.82Ga Heusler alloys with a coupled magnetostructural transition

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