Low-temperature-induced intermartensitic phase transformations in Ni-Mn-Ga single crystal

A sequence of temperature-induced, reversible inter-martensitic transformations (IMTs) has been found to occur in single-crystalline Ni52.6Mn23.6Ga23.8. The low-temperature forward IMTs occur more than 100 K below the forward martensitic transformation, and result to be controlled by the internal stresses stored in the martensitic state after the performed transformation sequence; while this fact causes a notable variability of the forward transformation temperatures for different specimens, the corresponding reverse transformations are much more reproducible. The temperature hysteresis of the IMTs is as high as 100 K, while the parent-martensite transformation shows 10 K hysteresis. TEM observations have confirmed the transformation sequence L21→10M→14M→2M.