Martensitic microstructure and its damping behavior in Ni52 Mn16 Fe8 Ga24 single crystals

In the present study, the martensitic microstructure and its damping behavior in Ni52 Mn16 Fe8 Ga24 single crystals were investigated using differential scanning calorimetry (DSC), x-ray diffraction (XRD), transmission electron microscopy (TEM), and dynamical mechanical analyzer (DMA). A structural transition from the cubic austenite to orthorhombic seven-layered modulation martensite was confirmed by XRD experiments and TEM observations. The measurements of temperature dependence of internal friction (IF) reveal an additional very broad IF peak in the low-temperature martensite phase. Moreover, the IF peak is frequency independent but it shows a pronounced amplitude dependence behavior, i.e., the IF peak broadens, decreases in height, and shifts to lower temperature with the increase of amplitude. The related mechanisms are also discussed in terms of the martensitic microstructure.