Crystallization temperature and activation energy of rf-sputtered near-equiatomic TiNi and Ti50Ni40Cu10 thin films

Amorphous thin films of Ti49.93Ni50.07 and Ti49.96Ni40.09Cu9.95 alloys were rf-sputtered onto a (1 0 0) Si-wafer and characterized by X-ray diffraction (XRD), DSC, and Auger electron spectrometer (AES) tests. The amorphous structure of the Ti49.93Ni50.07 films is found to be similar to that of TiXNi1−X rapidly quenched ribbons and mechanically alloyed powders, but more stable than Ti49.96Ni40.09Cu9.95 films, by comparing the wavenumbers (QP) of the broad XRD peaks. The crystalline activation energy, Ea, and the onset crystallization temperature, TX, for a 30°C/min DSC heating rate of the Ti49.96Ni40.09Cu9.95 and Ti49.93Ni50.07 films are 388 kJ/mol, 488°C, and 416 kJ/mol and 511°C, respectively. This also suggests that the amorphous Ti49.96Ni40.09Cu9.95 thin film is less stable than the Ti49.93Ni50.07 film, and can be explained in terms of the enthalpy of mixing. The TX values of amorphous TiXNi1−X materials fabricated by the sputtering technique, by rapid quenching and by mechanical alloying are also compared and discussed.