Possibilities, performance and challenges of nitinol alloy fabricated by Directed Energy Deposition and Powder Bed Fusion for biomedical implants

Shape Memory Alloys (SMAs) are metals with unique properties that allow them to revert to a predefined shape when heated. Thermal and thermo-mechanical treatments can significantly impact the phase change of an existing element. Nitinol (Ni-Ti), often identified as nitinol alloys, is a shape memory alloy widely employed in various applications, including biomedical, aerospace, automotive, and MEMS devices. The Nitinol shape memory alloy was immensely popular among many qualities like biocompatibility, superelasticity, corrosion resistance, damping, low stiffness, and exquisite features. Conventional techniques fail to manufacture high-quality complex Nitinol components because of several material properties, including sensitivity to composition and manufacturing heat gradients. Modern additive manufacturing (AM) techniques like Powder Bed Fusion (PBF) and Directed Energy Deposition (DED) are used to solve these issues, which may create net or nearly net-shaped items. The use of AM methods to create biomedical implants, devices, and other components employing Ni-Ti alloys has grown significantly and drawn the attention of several researchers. The current study has discussed an extensive analysis of numerous applications, potential focus areas, additive manufacturing processes, fabrication challenges, functional performance and post-processing methods used for SMAs.