Shape memory behavior of Fe–Pd alloy thin films prepared by dc magnetron sputtering

Fe–Pd films have been deposited onto fused quartz and silicon substrates by dc magnetron sputtering. When an arc-melted and homogenized Fe–30at.% Pd alloy disk was used as a sputtering target, Fe–Pd films fabricated was shown to contain about 24 at.% Pd under the deposition condition used. The target configuration was then modified by placing Pd wires on the target so as to control the Pd content of films with an accuracy of 1 at.% Pd. Fe–Pd films containing 28.5 at.% Pd underwent a thermoelastic fcc-to-fct martensite transformation after annealing at 900 °C followed by quenching into iced water. Apparently, the reverse transformation was also thermoelastic and the thermoelastic transformations occurred repeatedly upon thermal cycling. Some of the Fe–28.5at.% Pd films were peeled off from the quartz substrate and they showed SM effects upon heating after deformation. A diaphragm-shaped free-standing film was also fabricated on a thin Si substrate. This film showed attractive transformation characteristics, including a narrow transformation hysteresis loop of about 4 °C and a small temperature difference between Mf and Af (about 10 °C) in addition to Ms (43 °C) close to room temperature. This diaphragm-shaped film showed a reversible ballooning behavior with a maximum strain of about 0.05% upon thermal cycling.