Nitinol (NiTi) Superelastic

Nitinol (NiTi) is a nickel-titanium shape-memory and superelastic alloy that exhibits remarkable strain recovery—when deformed, it returns to its original shape upon unloading or heating, depending on the alloy's thermal state. This property stems from a reversible phase transformation between austenite and martensite crystal structures, making it fundamentally different from conventional metals. In superelastic form (used at room temperature above the austenite finish temperature), Nitinol absorbs and releases large elastic deformations repeatedly without permanent set, enabling designs where flexibility and damage tolerance are critical. The alloy is widely deployed in medical devices—stents, guidewires, orthodontic wires, and surgical instruments—where its biocompatibility, fatigue resistance, and ability to conform to complex geometries while maintaining structural integrity are essential; it is also found in aerospace actuators, seismic dampers, and precision mechanical switches where its unique combination of elasticity and hysteretic energy absorption outperforms conventional springs or elastic materials.