Switzerland: iron-based shape memory alloys with low activation

Licensing opportunity | Development opportunity

Scientists at Empa, the Swiss Federal Laboratories for Materials Testing and Research, have developed an iron-based shape memory alloy (SMA) with relatively low (120°C–200°C) phase transformation temperatures.

The alloy is suitable for applications, such as in concrete structures, for which moderate phase transformation temperatures are needed, or in mechanical engineering, for example clamping devices, where high recovery stresses are required.

Shape memory alloys are often applied. among other things. as actuators. They can used for devices that transform thermal energy directly into mechanical work. They can also be used in special applications, where conventional electric or hydraulic actuators cannot be used due to space or weight limitations.

To date, SMAs have been based on nickel titanium (NiTi) alloys, which are very expensive and are generally activated at temperatures ranging from approximately -50°C to approximately 150°C. While iron-based SMAs would be a cost-effective alternative to alloys based on NiTi, the temperature range for activation of conventional iron-based SMAs has been significantly above 200°C, and their shape memory properties rather poor in comparison with NiTi alloys.

The iron-based SMA developed at Empa has significantly lower activation temperatures, in the range of 120°C – 200°C. Overall, it combines the low activation temperature range of NiTi alloys, with the low cost of iron based SMAs, an excellent shape recovery and high recovery stress. These properties of the new SMA make it suitable for large volume applications. It could be used in sectors including civil and mechanical engineering, automotive applications or transportation.

The alloy is expected to exhibit good corrosion resistance due to the relatively high level of nickel and chromium used as alloying elements.