Processing and properties of customized alloys for elastocaloric applications

Today, Shape Memory Alloys based on Nickel Titanium are mostly known for superelastic applications in the medical field, and actuator applications, using the shape memory effect. The emerging application field of elastocalorics combines many of the requirements of both existing technologies. With the potential of both helping to make cooling and heating more sustainable and at the same time multiplying the world’s market of Shape Memory alloy production, it is a very interesting field to be active in as an SMA producer. While tube and wire are the most commonly used semi-finished products in medical applications, wire and compression springs represent the major part of actuator components. For Elastocalorics, it is not yet clear which geometry will prevail.

Systems based on tension, compression and torsion have been presented by the community, each with its own merits but also disadvantages. What all have in common is that most prototype systems are built with available, of the shelf material for medical applications. What all also have share is that this material is not really the best fit for Elastocalorics, and thus, the need of customized Shape Memory Alloys, based on changing alloy compositions. Hysteresis, material’s COP (Coefficient of performance) and cyclic stability are among the most important requirements. For cascaded systems, also precisely controlled alloy-variations with close sequences of changing Af-temperatures.

In this work, we present our recent results on the processing, training and characterization of binary and quaternary alloys, wire and sheet/ribbon for elastocaloric applications.