Microstructure and martensitic transformation of Ni–Mn–Ga–Ti ferromagnetic shape memory alloys

The effect of Ti addition on the microstructure and martensitic transformation of polycrystalline Ni53Mn23.5Ga23.5−xTix (x = 0, 0.5, 2, 3.5, 5) ferromagnetic shape memory alloys was investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The results show that Ni–Mn–Ga–Ti alloys exhibit thermoelastic martensitic transformations. The martensitic transformation temperatures of Ni53Mn23.5Ga23.5−xTix alloys increase with the increase of Ti content, while the martensite structure of these alloys is five-layered martensite at room temperature. In addition, some Ti-rich precipitates are observed in aged Ni53Mn23.5Ga23.5−xTix alloys.