Large tensile superelasticity from intermartensitic transformations in Ni49Mn28Ga23 single crystal

A multistep superelastic behavior, with up to a 12% strain, is reported in a (001)p-oriented Ni49Mn28Ga single crystal. The observed behavior is produced by intermartensitic transformations during the tensile stress-strain measurements at temperatures between -140 °C and 60°C. The tensile stress-temperature phase diagram and the stress dependence of the intermartensitic transformation entropies have been obtained. These results provide important input for theoretical modeling of the phase transformations in these alloys and show promising mechanical properties of the classical Ni-Mn-Ga ferromagnetic shape memory alloys. C P