Ti-Pd-Ni high temperature shape memory thin films formed with carousel type magnetron sputtering apparatus

Abstract
High temperature shape memory thin films of Ti-Pd-Ni were formed with a carousel type magnetron sputtering apparatus. Four kinds of films with different compositions (a Ti-rich, a near stoichiometric, and two (Pd, Ni)-rich films) were prepared by independently applying D.C. powers to each pure metal target. The near stoichiometric sample with a composition of Ti_49.5Pd_28.5Ni_22.0 was found to consist mainly of a Ti (Pd, Ni) phase, and showed a shape memory effect at about 500K with a recoverable transformation strain of 2.9% and a plastic strain of 0.3% at 160MPa. The Ti-rich film with a composition of Ti_51.2Pd_27.0Ni_21.8 was found to contain a TiPd₂ type second phase, and showed a shape memory effect at about 490K with a smaller recoverable transformation strain of 1.5% and a smaller plastic strain of 0.05% than those of the near stoichiometric film. One of the (Pd, Ni)-rich films with a composition of Ti_47.9Pd_29.8Ni_22.3 was found to possess both B2 and B19 phases at ambient temperature, and showed a shape memory effect at 360K with a recoverable transformation strain of 2.5% almost as large as the near stoichiometric film, and showed a plastic strain of 0.05% as small as that of the Ti-rich film.