Formgedächtniswerkstoffen

Formgedächtnis refers to the ability of certain materials to return to their original shape after being deformed. This property is most commonly associated with shape memory alloys (SMAs), but can also be observed in shape memory polymers and even some biological tissues. The phenomenon is based on a reversible solid-state phase transformation. When the material is deformed at a lower temperature, it enters a less stable phase. Upon heating above a specific transition temperature, the material reverts to its original, more stable phase, thereby recovering its initial shape. This recovery process is driven by the internal energy minimization.

The most well-known SMAs are nickel-titanium (NiTi) alloys, also known as Nitinol. These materials exhibit a significant shape recovery strain, making them suitable for a wide range of applications. The transition temperatures of SMAs can be tailored through precise control of their chemical composition and heat treatment. This allows for the development of materials that respond to specific temperature changes.

The applications of formgedächtnis are diverse and continue to expand. They are used in medical devices such as stents and orthodontic wires, where their ability to recover their shape at body temperature is crucial. In aerospace and automotive industries, they are employed in actuators, couplings, and fasteners. Consumer products also benefit from this property, with examples including self-deploying structures and temperature-sensitive valves. The development of new formgedächtnis materials with enhanced properties and novel functionalities remains an active area of research.