Shape memory alloys. Ultralow-fatigue shape memory alloy films

Christoph Chluba; Wenwei Ge; Rodrigo Lima de Miranda; Julian Strobel; Lorenz Kienle; Eckhard Quandt; Manfred Wuttig

doi:10.1126/science.1261164

Shape memory alloys. Ultralow-fatigue shape memory alloy films

Science. 2015 May 29;348(6238):1004-7. doi: 10.1126/science.1261164.

Authors

Christoph Chluba¹, Wenwei Ge², Rodrigo Lima de Miranda¹, Julian Strobel¹, Lorenz Kienle¹, Eckhard Quandt³, Manfred Wuttig⁴

Affiliations

¹ Institute for Materials Science, Faculty of Engineering, University of Kiel, Kiel, Germany.
² Department of Materials Science and Engineering, University of Maryland, College Park, MD, USA.
³ Institute for Materials Science, Faculty of Engineering, University of Kiel, Kiel, Germany. [email protected] [email protected].
⁴ Department of Materials Science and Engineering, University of Maryland, College Park, MD, USA. [email protected] [email protected].

PMID: 26023135
DOI: 10.1126/science.1261164

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.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.