title: Shape memory alloys. Ultralow-fatigue shape memory alloy films.
abstract: Functional shape memory alloys need to operate reversibly and repeatedly. Quantitative measures of reversibility include the relative volume change of the participating phases and compatibility matrices for twinning. But no similar argument is known for repeatability. This is especially crucial for many future applications, such as artificial heart valves or elastocaloric cooling, in which more than 10 million transformation cycles will be required. We report on the discovery of an ultralow-fatigue shape memory alloy film system based on TiNiCu that allows at least 10 million transformation cycles. We found that these films contain Ti2Cu precipitates embedded in the base alloy that serve as sentinels to ensure complete and reproducible transformation in the course of each memory cycle.
authors.affiliation: Institute for Materials Science, Faculty of Engineering, University of Kiel, Kiel, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Chluba
authors.affiliation: Department of Materials Science and Engineering, University of Maryland, College Park, MD, USA.
authors.forename: Wenwei
authors.initials: W
authors.lastname: Ge
authors.affiliation: Institute for Materials Science, Faculty of Engineering, University of Kiel, Kiel, Germany.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Lima de Miranda
authors.affiliation: Institute for Materials Science, Faculty of Engineering, University of Kiel, Kiel, Germany.
authors.forename: Julian
authors.initials: J
authors.lastname: Strobel
authors.affiliation: Institute for Materials Science, Faculty of Engineering, University of Kiel, Kiel, Germany.
authors.forename: Lorenz
authors.initials: L
authors.lastname: Kienle
authors.affiliation: Institute for Materials Science, Faculty of Engineering, University of Kiel, Kiel, Germany. eq@tf.uni-kiel.de wuttig@umd.edu.
authors.forename: Eckhard
authors.initials: E
authors.lastname: Quandt
authors.affiliation: Department of Materials Science and Engineering, University of Maryland, College Park, MD, USA. eq@tf.uni-kiel.de wuttig@umd.edu.
authors.forename: Manfred
authors.initials: M
authors.lastname: Wuttig