Shape memory thin films

Shape memory thin film technology is of great interest due to the generated special material properties and the possibility of a cost effective batch fabrication. Furthermore, the fabrication of micro-patterned films using magnetron sputtering, UV lithography, and wet etching has a great potential to overcome limitations of conventional device manufacturing. The talk will address applications in minimally invasive medicine (e.g. aneurysm treatments), as well as in micro-actuators or materials for elastocaloric cooling.

Such functional shape memory alloys need to operate reversibly and repeatedly. This is especially crucial for many future high cycle applications, e.g. elastocaloric cooling, where millions of transformation cycles will be required. In recent years, examples of unprecedented functional and structural fatigue resistance and reduced hysteresis in shape memory alloys have been achieved by combining conditions of supercompatibility between phases with suitable grain size and a favorable array of fine precipitates. The relative roles of these factors, especially in the case of the more demanding stress-induced phase transformations, will be discussed.

Funding by different DFG grants is gratefully acknowledged.