SYMPOSIA PAPER Published: 01 January 2001

Thermomechanical Characterization of Nickel-Titanium Copper Shape Memory Alloy Films


In an effort to develop a more extensive model for the thermomechanical behavior of shape memory alloy (SMA) films, a novel characterization method has been developed. This automated test has been tailored to characterize films for use in micro-electromechanical system (MEMS) actuators. The shape memory effect in NiTiCu is seen in the solid-state phase transformation from an easily deformable low-temperature state to a “shape remembering” high-temperature state. The accurate determination of engineering properties for these films necessitates measurements of both stress and strain in microfabricated test structures over the full range of desired deformation. Our various experimental methods (uniaxial tensile tests, bimorph curvature tests, and diaphragm bulge tests) provide recoverable stress and strain data and the stress-strain relations for these films. Tests were performed over a range of temperatures by resistive heating or ambient heating. These measurements provide the results necessary for developing active SMA structural film design models

Author Information

Seward, KP
Lawrence Livermore National Laboratory, Livermore, CA
Ramsey, PB
Lawrence Livermore National Laboratory, Livermore, CA
Krulevitch, P
Lawrence Livermore National Laboratory, Livermore, CA
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Developed by Committee: E08
Pages: 293–305
DOI: 10.1520/STP10996S
ISBN-EB: 978-0-8031-5458-2
ISBN-13: 978-0-8031-2889-7