Abstract: A method for fabricating a bi-layer thin film is provided. A first alloy is deposited onto a substrate using a first alloy target to form a first layer of the bi-layer thin film. The first layer may comprise greater than 50 atomic % titanium (Ti) and/or less than 50 atomic % nickel (Ni). The first alloy may be deposited onto the substrate at a first temperature (e.g., room temperature). The substrate may be made of a polymer material, such as poly (4,4?-oxydiphenylene-pyromellitimide) (e.g., Kapton™). A second alloy is deposited onto the first layer using a second alloy target to form a second layer of the bi-layer thin film. The second layer may comprise greater 50 atomic % nickel and/or less than 50 atomic % titanium. The second alloy may be deposited onto the first layer at a second temperature (e.g., room temperature). The bi-layer thin film may exhibit pseudo elasticity and shape memory effect (SME).

Abstract: A method for fabricating a bi-layer thin film is provided. A first alloy is deposited onto a substrate using a first alloy target to form a first layer of the bi-layer thin film. The first layer may comprise greater than 50 atomic % titanium (Ti) and/or less than 50 atomic % nickel (Ni). The first alloy may be deposited onto the substrate at a first temperature (e.g., room temperature). The substrate may be made of a polymer material (e.g., Kapton). A second alloy is deposited onto the first layer using a second alloy target to form a second layer of the bi-layer thin film. The second layer may comprise greater 50 atomic % nickel and/or less than 50 atomic % titanium. The second alloy may be deposited onto the first layer at a second temperature (e.g., room temperature). The bi-layer thin film may exhibit pseudo elasticity and shape memory effect (SME).

Abstract: NiTi thin films with composition gradient have the added feature of an intrinsic two-way shape memory effect. According to the invention, a method of fabrication of Ni-rich/(NiTiCu) Ti-rich bi-layer thin film is disclosed. The bi-layer thin film formed compositional gradients at the interface of the films through diffusion. The bi-layer presented a combined pseudo elastic behavior and shape memory effect with a reduced hysteresis. The combination of pseudo elastic with shape memory effect produces an intrinsic two-way shape memory effect (TWSME). This behavior achieved without needing complicated heat treatment and training process. Therefore, it is compatible with MEMS processing.