A Nitinol wire returns to its original, pre-set shape after being heated due to a phenomenon called the shape memory effect. This ability comes from a reversible, temperature-dependent change in the material's atomic structure, not from a simple expansion or melting. | Fadhel Mahdi

Shape Memory Alloys (SMAs), such as Nitinol, are unique metals that can be bent or deformed at low temperatures but return to their original, pre-set shape when heated. This remarkable behavior is due to a solid-state phase transformation between two distinct crystal structures: martensite and austenite. At cooler temperatures, the alloy exists in the martensite phase — a softer, more flexible structure with lower symmetry. In this state, the material can be reshaped without causing permanent ch

NiTiNOL’s shape-memory effect arises from a reversible phase transformation between its austenite and martensite crystal structures. At higher temperatures, in the austenite phase, NiTiNOL maintains a specific shape due to its ordered crystal structure. When cooled below a transition temperature, it transforms into the martensite phase, becoming flexible and deformable. This is where you can bend the wire and deform it into any shape you’d like. Upon heating above the transition temperature (the

Shape memory effect (Nitinol) #metallurgy | Metallurgical engineering