NiTiCu shape memory alloy produced by powder technology

The main aim of presented work was to find the sintering conditions (temperature and time) for manufacturing of a Ni(50−X)Ti50CuX alloy (where X = 2, 3, 5, 10, 15, 20 and 25 at%) by powder technology. Various conditions of sintering considering temperature and time were applied to compacted powders. Sintering temperature varied from 850 to 1100 °C and sintering time was chosen from a range of 5–50 h, respectively. Microstructure, structure, chemical composition and thermal behavior of sintered blends were studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray diffraction. Homogenous alloys, containing lower addition of copper (less than 10 at%), were sintered at 940 °C for 7 h. For higher copper content (10–25 at%) lower sintering temperature 850 °C but longer sintering time was preferred (20 h). The quality of the alloy was characterized by porosity and density. In sintered blends non-transformable phases Ti2(Ni,Cu) and (Ni,Cu)3Ti, which posses the crystal structure of Ti2Ni and Cu3Ti, respectively, were found. Despite the fact that same sintering conditions lead to an increase of inhomogeneity all sintered alloys reveal the presence of the reversible martensitic transformation. Obtained results allowed to optimize sintering condition for NiTiCu shape memory alloy manufacturing.