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A shape memory alloy (SMA) is a functional material which can return to its pre-deformed shape when experiencing external thermal or mechanical loads. This so-called shape memory effect is caused by the solid-state phase transition between the martensitic and austenitic phases. SMAs also display pseudoelasticity or superelasticity, which is characterized by a reversible stress-strain behavior with higher strain values than classic alloys. These unique properties make SMAs attractive for applications such as medical implants, stents, actuators, sensors, foldable devices, among others [1, 2]. Copper zinc aluminum (CuZnAl), copper aluminum nickel (CuAlNi), and Nitinol (NiTi) are the three most studied SMAs and are commercially available. Particularly, Nitinol, which is a blend of nickel and titanium, is the most commonly used one because of its stability and biocompatibility [3].

In spite of its great potential for new product concepts, several challenges exist in the fabrication of SMAs in traditional manufacturing methods such as casting and rolling, including difficulty of controlling material impurities, localized concentrations of materials for specific applications, fine tuning mechanical properties, as well as eliminating or introducing porosity in the structures [4, 5]. In recent years, researchers have examined the properties of SMAs made by additive manufacturing (AM) techniques. AM overcomes some of these challenges and potentially allows engineers to customize the structures and control the localized compositions and processing temperatures for SMAs.