A low temperature in-situ crystalline TiNi shape memory thin film deposited by magnetron sputtering

• Austenite (B2) peak was observed as deposited film without any thermal treatment.
• DC magnetron sputtering with pulsed dc substrate voltage been shown to be effective to obtain crystalline TiNi films at low substrate temperature.
• Final plasma temperature at R7 film (as-deposited crystalline TiNi film) was 290°C.
• TiNi films showed single-stage phase transformation.

ABSTRACTTiNi films deposited by magnetron sputtering usually have amorphous structure and must be annealed at high temperature to obtain crystallization. We have synthesized an in-situ fully crystalline TiNi shape memory thin film at low temperature by dc magnetron sputtering. Application of pulsed direct current to the substrate is effective to obtain a crystalline TiNi film. Nine different conditions were used for deposition in silicon wafer and thin copper plate substrates. Structural properties and phase transformation temperatures of the TiNi films were investigated. To examine the structural properties of the films, XRD, SEM and EDS techniques were used. Austenitic and martensitic phase transformation temperatures were observed via DSC (differential scanning calorimeter) tests. TiNi (110) B2 austenite peaks were observed in the Run7 film. The crystalline Run7 TiNi film showed single-stage phase transformation (B19 to B2 on heating and B2 to B19 on cooling).