Actuating Bimorph Microstructures with Magnetron-Sputtered Ti-Ni-Cu Shape Memory Alloy Films

Area of Science:

• Materials Science
• Mechanical Engineering
• Nanotechnology

Background:

• Shape-memory alloys (SMAs) like Ti-Ni-Cu are crucial for microactuation.
• Previous models for Ni-Ti/Si bimorphs provide a foundation for new studies.
• Non-metallic substrates offer unique advantages for SMA film applications.

Purpose of the Study:

• To investigate microactuation generation using Ti-Ni-Cu SMA films on non-metallic substrates.
• To adapt and apply a previously developed bimorph model for these new material systems.
• To analyze the impact of composition and deposition on SMA film properties and actuation.

Main Methods:

• Magnetron sputtering deposition of Ti-Ni-Cu films on Si and Kapton substrates at elevated temperatures.
• Characterization using X-ray diffraction and scanning electron microscopy for microstructure and composition analysis.
• Differential scanning calorimetry and electrical resistance measurements to determine phase transformation behavior.

Main Results:

• Ti-Ni-Cu films with ultra-fine grains were achieved at a 550 °C deposition temperature.
• A composition near Ti50Ni35Cu15 resulted in narrow thermal hysteresis with retained shape recovery.
• The study successfully modeled the actuation of cantilever-type bimorphs with Si and Kapton substrates.

Conclusions:

• Ti-Ni-Cu SMA films on non-metallic substrates are viable for microactuation.
• The developed model accurately predicts the performance of these novel bimorph structures.
• Optimized deposition and composition enable efficient microactuation with desirable SMA properties.